Holy Roman Empire

Initially, following Charlemagne's coronation in 800, the realm was simply referred to as the "Roman Empire". The term sacrum ("holy", in the sense of "consecrated") in connection with the medieval Roman Empire was used beginning in 1157 under Frederick I Barbarossa ("Holy Empire"): the term was added to reflect Frederick's ambition to dominate Italy and the Papacy. The form "Holy Roman Empire" is attested from 1254 onward.

The exact term "Holy Roman Empire" was not in use until the 13th century, before which the empire was referred to variously as universum regnum ("the whole kingdom", as opposed to the regional kingdoms), imperium christianum ("Christian empire"), or Imperium Romanum ("Roman empire"), but the Emperor's legitimacy always rested on the concept of translatio imperii, that he held supreme power inherited from the ancient emperors of Rome.

From the mid-13th century onward, the Holy Roman Empire came to be more firmly associated with a German (deutsch) identity. By around 1500, contemporary sources often referred to it simply as "Germany", reflecting its identification as a specifically German polity. In a decree following the Diet of Cologne in 1512, the name was changed to the "Holy Roman Empire of the German Nation" (German: Heiliges Römisches Reich Deutscher Nation, Latin: Sacrum Imperium Romanum Nationis Germanicae), a form first used in a document in 1474. The adoption of this new name coincided with the loss of imperial territories in Italy and Burgundy to the south and west by the late 15th century, but also to emphasize the new importance of the German Imperial Estates in ruling the Empire due to the Imperial Reform. The Hungarian denomination "German Roman Empire" (Hungarian: Német-római Birodalom) is the shortening of this.

By the end of the 18th century, the term "Holy Roman Empire of the German Nation" fell out of official use. Contradicting the traditional view concerning that designation, Hermann Weisert has argued in a study on imperial titulature that, despite the claims of many textbooks, the name "Holy Roman Empire of the German Nation" never had an official status and points out that documents were thirty times as likely to omit the national suffix as include it. Similarly, Peter Wilson states that "of the German Nation" was "appended more frequently after 1512 without becoming the Empire's official title – despite numerous later claims to the contrary", and that "German historians are far more likely to refer to [the Empire] as 'of the German nation' than were its actual inhabitants." Still, the full name including "of the German Nation" was used in official documents and by contemporary chroniclers alike.

In a famous assessment of the name, the political philosopher Voltaire remarked sardonically: "This body which was called and which still calls itself the Holy Roman Empire was in no way holy, nor Roman, nor an empire." In the modern period, the Empire was often informally called the "German Empire" (Deutsches Reich) or "Roman-German Empire" (Römisch-Deutsches Reich). After its dissolution through the end of the German Empire, it was often called "the old Empire" (das alte Reich). Beginning in 1923, early 20th-century German nationalists and Nazi Party propaganda would identify the Holy Roman Empire as the "First" Reich (Erstes Reich, Reich meaning empire), with the German Empire as the "Second" Reich and what would eventually become Nazi Germany as the "Third" Reich.

David S. Bachrach opines that the Ottonian kings actually built their empire on the back of military and bureaucratic apparatuses as well as the cultural legacy they inherited from the Carolingians, who ultimately inherited these from the Late Roman Empire. He argues that the Ottonian empire was hardly an archaic kingdom of primitive Germans, maintained by personal relationships only and driven by the desire of the magnates to plunder and divide the rewards among themselves but instead, notable for their abilities to amass sophisticated economic, administrative, educational and cultural resources that they used to serve their enormous war machine.

Until the end of the 15th century, the empire consisted of three major blocks—Germany, Italy and Burgundy. Effectively, the Kingdom of Germany became the sole remaining component. The Burgundian territories were lost to France. Although the Italian territories were formally part of the empire, the territories were ignored in the Imperial Reform and splintered into numerous de facto independent territorial entities. The status of Italy in particular varied throughout the 16th to 18th centuries. Some territories like Piedmont-Savoy became increasingly independent, while others became more dependent due to the extinction of their ruling noble houses causing these territories to often fall under the dominions of the Habsburgs and their cadet branches. Barring the loss of Franche-Comté in 1678, the external borders of the Empire did not change noticeably from the Peace of Westphalia – which acknowledged the exclusion of Switzerland and the Northern Netherlands, and the French protectorate over Alsace – to the dissolution of the Empire. At the conclusion of the Napoleonic Wars in 1815, most of the Holy Roman Empire was included in the German Confederation, with the main exceptions being the Italian states.

As Roman power in Gaul declined during the 5th century, local Germanic tribes assumed control. In the late 5th and early 6th centuries, the Merovingians, under Clovis I and his successors, consolidated Frankish tribes and extended hegemony over others to gain control of northern Gaul and the middle Rhine river valley region. By the middle of the 8th century, the Merovingians were reduced to figureheads, and the Carolingians, led by Charles Martel, became the de facto rulers. In 751, Martel's son Pepin became King of the Franks, and later gained the sanction of the Pope. The Carolingians would maintain a close alliance with the Papacy. In 768, Pepin's son Charlemagne became King of the Franks and began an extensive expansion of the realm. He eventually incorporated the territories of present-day France, Germany, northern Italy, the Low Countries and beyond, linking the Frankish kingdom with Papal lands.

Although antagonism about the expense of Byzantine domination had long persisted within Italy, a political rupture was set in motion in earnest in 726 by the iconoclasm of Emperor Leo III the Isaurian, in what Pope Gregory II saw as the latest in a series of imperial heresies. In 797, the Eastern Roman Emperor Constantine VI was removed from the throne by his mother, Empress Irene, who declared herself sole ruler. As the Latin Church only regarded a male Roman emperor as the head of Christendom, Pope Leo III sought a new candidate for the dignity, excluding consultation with the patriarch of Constantinople.

Charlemagne's good service to the Church in his defense of Papal possessions against the Lombards made him the ideal candidate. On Christmas Day of 800, Pope Leo III crowned Charlemagne emperor, restoring the title in the West for the first time in over three centuries. This can be seen as symbolic of the papacy turning away from the declining Byzantine Empire toward the new power of Carolingian Francia. Charlemagne adopted the formula Renovatio imperii Romanorum ("renewal of the Roman Empire"). In 802, Irene was overthrown and exiled by Nikephoros I and henceforth there were two Roman emperors.

After Charlemagne died in 814, the imperial crown passed to his son, Louis the Pious. Upon Louis' death in 840, it passed to his son Lothair, who had been his co-ruler. By this point the territory of Charlemagne was divided into several territories (cf. Treaty of Verdun, Treaty of Prüm, Treaty of Meerssen and Treaty of Ribemont), and over the course of the later 9th century the title of emperor was disputed by the Carolingian rulers of the Western Frankish Kingdom or West Francia and the Eastern Frankish Kingdom or East Francia, with first the western king (Charles the Bald) and then the eastern (Charles the Fat), who briefly reunited the Empire, attaining the prize.

In the 9th century, Charlemagne and his successors promoted the intellectual revival, known as the Carolingian Renaissance. Some, like Mortimer Chambers, opine that the Carolingian Renaissance made possible the subsequent renaissances (even though by the early 10th century, the revival already diminished). After the death of Charles the Fat in 888, Carolingian rule in the Roman Empire came to an end. According to Regino of Prüm, the parts of the realm "spewed forth kinglets", and each part elected a kinglet "from its own bowels". The last such emperor was Berengar I of Italy, who died in 924.

Around 900, East Francia's autonomous stem duchies (Franconia, Bavaria, Swabia, Saxony, and Lotharingia) reemerged. After the Carolingian king Louis the Child died without issue in 911, East Francia did not turn to the Carolingian ruler of West Francia to take over the realm but instead elected one of the dukes, Conrad of Franconia, as Rex Francorum Orientalium. On his deathbed, Conrad yielded the crown to his main rival, Henry the Fowler of Saxony (r. 919–936), who was elected king at the Diet of Fritzlar in 919. Henry reached a truce with the raiding Magyars, and in 933 he won a first victory against them in the Battle of Riade.

Henry died in 936, but his descendants, the Liudolfing (or Ottonian) dynasty, would continue to rule the Eastern kingdom or the Kingdom of Germany for roughly a century. Upon Henry the Fowler's death, Otto, his son and designated successor, was elected king in Aachen in 936. He overcame a series of revolts from a younger brother and from several dukes. After that, the king managed to control the appointment of dukes and often also employed bishops in administrative affairs. He replaced leaders of most of the major East Frankish duchies with his own relatives. At the same time, he was careful to prevent members of his own family from making infringements on his royal prerogatives.

In 951, Otto came to the aid of Queen Adelaide of Italy, defeating her enemies, marrying her, and taking control over Italy. In 955, Otto won a decisive victory over the Magyars in the Battle of Lechfeld. In 962, Otto was crowned emperor by Pope John XII, thus intertwining the affairs of the German kingdom with those of Italy and the Papacy. Otto's coronation as emperor marked the German kings as successors to the empire of Charlemagne, which through the concept of translatio imperii, also made them consider themselves as successors to Ancient Rome. The flowering of arts beginning with Otto the Great's reign is known as the Ottonian Renaissance, centered in Germany but also happening in Northern Italy and France.

Otto created the imperial church system, often called "Ottonian church system of the Reich", which tied the great imperial churches and their representatives to imperial service, thus providing "a stable and long-lasting framework for Germany". During the Ottonian era, imperial women played a prominent role in political and ecclesiastic affairs, often combining their functions as religious leader and advisor, regent or co-ruler, notably Matilda of Ringelheim, Eadgyth, Adelaide of Italy, Theophanu, and Matilda of Quedlinburg.

In 963, Otto deposed John XII and chose Leo VIII as the new pope (although John XII and Leo VIII both claimed the papacy until 964, when John XII died). This also renewed the conflict with the Byzantine emperor, especially after Otto's son Otto II (r. 967–983) adopted the designation imperator Romanorum. Still, Otto II formed marital ties with the east when he married the Byzantine princess Theophanu. Their son, Otto III, came to the throne only three years old, and was subjected to a power struggle and series of regencies until his age of majority in 994. Up to that time, he remained in Germany, while a deposed duke, Crescentius II, ruled over Rome and part of Italy, ostensibly in his stead.

In 996 Otto III appointed his cousin Gregory V the first German pope. A foreign pope and foreign papal officers were seen with suspicion by Roman nobles, who were led by Crescentius II to revolt. Otto III's former mentor Antipope John XVI briefly held Rome, until the Holy Roman emperor seized the city. Otto died young in 1002, and was succeeded by his cousin Henry II, who focused on Germany. Otto III's (and his mentor Pope Sylvester's) diplomatic activities coincided with and facilitated the Christianization and the spread of Latin culture in different parts of Europe. They coopted a new group of nations (Slavic) into the framework of Europe, with their empire functioning, as some remark, as a "Byzantine-like presidency over a family of nations, centered on pope and emperor in Rome". This has proved a lasting achievement. Though, Otto's early death made his reign "the tale of largely unrealized potential".

Henry II died in 1024 and Conrad II, first of the Salian dynasty, was elected king only after some debate among dukes and nobles. This group eventually developed into the college of electors. The Holy Roman Empire eventually came to be composed of four kingdoms:

Kingdom of Germany (part of the empire since 962),

Kingdom of Italy (from 962 until 1801),

Kingdom of Bohemia (from 1002 as the Duchy of Bohemia and raised to a kingdom in 1198),

Kingdom of Burgundy (from 1032 to 1378).

Kings often employed bishops in administrative affairs and often determined who would be appointed to ecclesiastical offices. In the wake of the Cluniac Reforms, this involvement was increasingly seen as inappropriate by the Papacy. The reform-minded Pope Gregory VII was determined to oppose such practices, which led to the Investiture Controversy with King Henry IV (r. 1056–1106, crowned emperor in 1084).

Henry IV repudiated the pope's interference and persuaded his bishops to excommunicate the pope, whom he famously addressed by his birth name "Hildebrand" rather than his papal name "Gregory". The pope, in turn, excommunicated the king, declared him deposed, and dissolved the oaths of loyalty made to Henry. The king found himself with almost no political support and was forced to make the famous Walk to Canossa in 1077, by which he achieved a lifting of the excommunication at the price of humiliation. Meanwhile, the German princes had elected another king, Rudolf of Swabia.

Henry managed to defeat Rudolf, but was subsequently confronted with more uprisings, renewed excommunication, and even the rebellion of his sons. After his death, his second son, Henry V, reached an agreement with the Pope and the bishops in the 1122 Concordat of Worms. The political power of the Empire was maintained, but the conflict had demonstrated the limits of the ruler's power, especially in regard to the Church, and it robbed the king of the sacral status he had previously enjoyed. The pope and the German princes had surfaced as major players in the political system of the Holy Roman Empire.

As the result of Ostsiedlung, less populated regions of Central Europe (i.e. sparsely populated border areas in present-day Poland and the Czech Republic) received a significant number of German speakers. Silesia became part of the Holy Roman Empire as the result of the local Piast dukes' push for autonomy from the Polish Crown. From the late 12th century, the Duchy of Pomerania was under the suzerainty of the Holy Roman Empire and the conquests of the Teutonic Order made that region German-speaking.

When the Salian dynasty ended with Henry V's death in 1125, the princes chose not to elect the next of kin, but rather Lothair III, the moderately powerful but already old duke of Saxony. When he died in 1137, the princes again aimed to check royal power; accordingly they did not elect Lothair's favoured heir, his son-in-law, Henry the Proud of the Welf family, but Conrad III of the Hohenstaufen family, the grandson of Emperor Henry IV and nephew of Emperor Henry V. This led to over a century of strife between the two houses. Conrad ousted the Welfs from their possessions, but after his death in 1152, his nephew Frederick Barbarossa succeeded him and made peace with the Welfs, restoring his cousin Henry the Lion to his – albeit diminished – possessions.

The Hohenstaufen rulers increasingly lent land to "ministeriales", formerly non-free servicemen, who Frederick hoped would be more reliable than dukes. Initially used mainly for war services, this new class of people would form the basis for the later knights, another basis of imperial power. A further important constitutional move at Roncaglia was the establishment of a new peace mechanism for the entire empire, the Landfrieden, with the first imperial one being issued in 1103 under Henry IV at Mainz. This was an attempt to abolish private feuds, between the many dukes and other people, and to tie the emperor's subordinates to a legal system of jurisdiction and public prosecution of criminal acts – a predecessor of the modern concept of rule of law. Another new concept of the time was the systematic founding of new cities by the emperor and by the local dukes. These were partly a result of the explosion in population; they also concentrated economic power at strategic locations.

Overall population figures for the Holy Roman Empire are extremely vague and vary widely. The empire of Charlemagne may have had as many as 20 million people. Given the political fragmentation of the later Empire, there were no central agencies that could compile such figures. Nevertheless, it is believed the demographic disaster of the Thirty Years' War meant that the population of the Empire in the early 17th century was similar to what it was in the early 18th century; by one estimate, the Empire did not exceed 1618 levels of population until 1750. In the early 17th century, the electors held under their rule the following number of Imperial subjects:

Habsburg Monarchy: 5,350,000 (including 3 million in the Bohemian crown lands)

Electorate of Saxony: 1,200,000

Duchy of Bavaria (later Electorate of Bavaria): 800,000

Electoral Palatinate: 600,000

Electorate of Brandenburg: 350,000

Electorates of Mainz, Trier, and Cologne: 300–400,000 altogether

While not electors, the Spanish Habsburgs had the second highest number of subjects within the Empire after the Austrian Habsburgs, with over 3 million in the early 17th century in the Burgundian Circle and Duchy of Milan. Peter Wilson estimates the Empire's population at 20 million in 1700, plus 5 million in Imperial Italy, a total of around 25 million. By 1800, he estimates the Empire's population at 29 million (excluding Italy), with another 12.6 million held by under Austrian and Prussian dominion outside of the Empire. According to a contemporary estimate of the Austrian War Archives for the first decade of the 18th century, the Empire – including Bohemia and the Spanish Netherlands – had a population of close to 28 million with a breakdown as follows:

65 ecclesiastical states with 14 percent of the total land area and 12 percent of the population;

45 dynastic principalities with 80 percent of the land and 80 percent of the population;

60 dynastic counties and lordships with 3 percent of the land and 3.5 percent of the population;

60 imperial towns with 1 percent of the land and 3.5 percent of the population;

Imperial knights' territories, numbering into the several hundreds, with 2 percent of the land and 1 percent of the population.

German demographic historians have traditionally worked on estimates of the population of the Holy Roman Empire based on assumed population within the frontiers of Germany in 1871 or 1914. More recent estimates use less outdated criteria, but they remain guesswork. One estimate based on the frontiers of Germany in 1870 gives a population of some 15–17 million around 1600, declined to 10–13 million around 1650 (following the Thirty Years' War). Other historians who work on estimates of the population of the early modern Empire suggest the population declined from 20 million to some 16–17 million by 1650. A credible estimate for 1800 gives 27–28 million inhabitants for the Empire (which at this point had already lost the remaining Low Countries, Italy, and the Left Bank of the Rhine in the 1797 Treaty of Campo Formio) with an overall breakdown as follows:

9 million Austrian subjects (including Silesia, Bohemia and Moravia);

4 million Prussian subjects;

14–15 million inhabitants for the rest of the Empire.

There are also numerous estimates for the Italian states that were formally part of the Empire:

Largest cities or towns of the Empire by year:

1050: Regensburg 40,000 people. Rome 35,000. Mainz 30,000. Speyer 25,000. Cologne 21,000. Trier 20,000. Worms 20,000. Lyon 20,000. Verona 20,000. Metz 16,000 people. Florence 15,000.

1300–1350: Milan 120,000 people. Florence 110,000 people. Genoa 90,000 people. Prague 77,000 people. Cologne 60,000 people. Verona 40,000 people. Padua 35,000 people. Erfurt 32,000 people. Metz 32,000 people. Regensburg 30,000 people. Speyer 25,000 people. Mainz 24,000 people. Aachen 21,000 people. Magdeburg 20,000 people. Nuremberg 20,000 people. Vienna 20,000 people. Danzig (now Gdańsk) 20,000 people. Straßburg (now Strasbourg) 20,000 people. Worms 20,000 people. Lübeck 15,000 people. Regensburg 11,000 people.

1500: Milan 100,000 people. Genoa 70,000 people. Prague 70,000.Florence 50,000 people. Cologne 45,000. Antwerp 40,000 people. Cremona 40,000 people. Nuremberg 38,000. Augsburg 30,000. Mantua 28,000 people. Lübeck 25,000. Breslau (now Wrocław) 25,000. Regensburg 22,000. Augsburg 20,000 people. Vienna 20,000. Straßburg (now Strasbourg) 20,000. Parma 19,000 people. Magdeburg 18,000. Modena 18,000 people. Pavia 16,000 people. Ulm 16,000. Hamburg 15,000.

1600: Milan 150,000. Prague 100,000. Vienna 50,000. Augsburg 45,000. Cologne 40,000. Nuremberg 40,000. Hamburg 40,000. Magdeburg 40,000. Breslau (now Wrocław) 40,000. Straßburg (now Strasbourg) 25,000. Lübeck 23,000. Ulm 21,000. Regensburg 20,000. Frankfurt am Main 20,000. Munich 20,000.

Catholicism constituted the single official religion of the Empire until 1555; the Holy Roman Emperor was always Catholic. Lutheranism was officially recognized in the Peace of Augsburg of 1555, and Calvinism in the Peace of Westphalia of 1648. Those two constituted the only officially recognized Protestant denominations, while various other Protestant confessions such as Anabaptism, Arminianism, etc. coexisted illegally within the Empire. Anabaptism came in a variety of denominations, including Mennonites, Schwarzenau Brethren, Hutterites, the Amish, and multiple other groups.

Following the Peace of Augsburg, the official religion of a territory was determined by the principle cuius regio, eius religio according to which a ruler's religion determined that of his subjects. The Peace of Westphalia abrogated that principle by stipulating that the official religion of a territory was to be what it had been on 1 January 1624, considered to have been a "normal year". Henceforth, the conversion of a ruler to another faith did not entail the conversion of his subjects.

In addition, all Protestant subjects of a Catholic ruler and vice versa were guaranteed the rights that they had enjoyed on that date. While the adherents of a territory's official religion enjoyed the right of public worship, the others were allowed the right of private worship (in chapels without either spires or bells). In theory, no one was to be discriminated against or excluded from commerce, trade, craft or public burial on grounds of religion. For the first time, the permanent nature of the division between the Christian churches of the empire was more or less assumed.

A Jewish minority existed in the Holy Roman Empire. The Holy Roman Emperors claimed the right of protection and taxation of all the Jews of the empire, but there were also large-scale massacres of Jews, especially at the time of the First Crusade and during the wars of religion in the 16th century.

The Holy Roman Empire was neither a centralized state nor a nation-state. Instead, it was divided into dozens – eventually hundreds – of individual entities governed by kings, dukes, counts, bishops, abbots, and other rulers, collectively known as princes. There were also some areas ruled directly by the Emperor. From the High Middle Ages onwards, the Holy Roman Empire was marked by an uneasy coexistence with the princes of the local territories who were struggling to take power away from it. To a greater extent than in other medieval kingdoms such as France and England, the emperors were unable to gain much control over the lands that they formally owned. Instead, to secure their own position from the threat of being deposed, emperors were forced to grant more and more autonomy to local rulers, both nobles and bishops. This process began in the 11th century with the Investiture Controversy and was more or less concluded with the 1648 Peace of Westphalia. Several Emperors attempted to reverse this steady dilution of their authority but were thwarted both by the papacy and by the princes of the Empire. In 1667, remarking on the "irregular" nature of the empire in its division of sovereignty between the princes and the Emperor, political philosopher Samuel von Pufendorf referred to it as a "monstrosity".

The number of territories represented in the Imperial Diet was considerable, numbering about 300 at the time of the Peace of Westphalia. Many of these Kleinstaaten ("little states") covered no more than a few square miles, or included several non-contiguous pieces, so the Empire was often called a Flickenteppich ("patchwork carpet").

An entity was considered a Reichsstand (imperial estate) if, according to feudal law, it had no authority above it except the Holy Roman Emperor himself. The imperial estates were these:

Territories ruled by a hereditary nobleman, such as a prince, archduke, duke, or count.

Territories in which secular authority was held by an ecclesiastical dignitary, such as an archbishop, bishop, or abbot. Such an ecclesiastic or Churchman was a prince of the Church. In the common case of a prince-bishop, this temporal territory (called a prince-bishopric) frequently overlapped with his often larger ecclesiastical diocese, giving the bishop both civil and ecclesiastical powers. Examples are the prince-archbishoprics of Cologne, Trier, and Mainz.

Free imperial cities and Imperial villages, which were subject only to the jurisdiction of the emperor.

The scattered estates of the free Imperial Knights and Imperial Counts, immediate subject to the Emperor but unrepresented in the Imperial Diet.

A sum total of 1,500 Imperial estates has been reckoned. For a list of Reichsstände in 1792, see List of Imperial Diet participants (1792).

The most powerful lords of the later empire were the Austrian Habsburgs, who ruled 240,000 km2 (93,000 sq mi) of land within the Empire in the first half of the 17th century, mostly in modern-day Austria and the Czech Republic. At the same time the lands ruled by the electors of Saxony, Bavaria, and Brandenburg (prior to the acquisition of Prussia) were all close to 40,000 km2 (15,000 sq mi); the Duke of Brunswick-Lüneburg (later the Elector of Hanover) had a territory around the same size. These were the largest of the German realms. The Elector of the Palatinate had significantly less at 20,000 km2 (7,700 sq mi), and the ecclesiastical Electorates of Mainz, Cologne, and Trier were much smaller, with around 7,000 km2 (2,700 sq mi). Just larger than them, with roughly 7,000–10,000 km2 (2,700–3,900 sq mi), were the Duchy of Württemberg, the Landgraviate of Hessen-Kassel, and the Duchy of Mecklenburg-Schwerin. They were roughly matched in size by the prince-bishoprics of Salzburg and Münster. The majority of the other German territories, including the other prince-bishoprics, were under 5,000 km2 (1,900 sq mi), the smallest being those of the Imperial Knights; around 1790 the Knights consisted of 350 families ruling a total of only 5,000 km2 (1,900 sq mi) collectively.

Imperial Italy was less fragmented politically, most of it c. 1600 being divided between Savoy (Savoy, Piedmont, Nice, Aosta), the Grand Duchy of Tuscany (Tuscany, bar Lucca), the Republic of Genoa (Liguria, Corisca), the duchies of Modena-Reggio and Parma-Piacenza (Emilia), and the Spanish Duchy of Milan (most of Lombardy), each with between half a million and one and a half million people. The Low Countries were also more coherent than Germany, being entirely under the dominion of the Spanish Netherlands as part of the Burgundian Circle, at least nominally. In 1792, 21 families (8 electors and 13 princely families) held 81 percent of the Empire's territory, plus all electoral and 56 of the 100 princely votes. These 21 families held 25 territories (some families had cadet branches e.g. the Bavarian and Palatinate Wittelsbachs), by far the largest being Austria and Prussia. Another 16.4 percent of the Empire was split between 151 ecclesiastical and secular lords, generally lacking princely status, with the majority of that 16.4 percent being held by a tenth of the lords. The remaining 2.6 percent of the Empire was split between 51 disconnected imperial cities and 400 families of Imperial Knights.

A prospective Emperor first had to be elected King of the Romans. German kings had been elected since the 9th century; at that point they were chosen by the leaders of the five most important tribes (the Salian Franks of Lorraine, Ripuarian Franks of Franconia, Saxons, Bavarians, and Swabians). In the Holy Roman Empire, the main dukes and bishops of the kingdom elected the King of the Romans. The imperial throne was transferred by election, but Emperors often ensured their own sons were elected during their lifetimes, enabling them to keep the crown for their families. This only changed after the end of the Salian dynasty in the 12th century.

In 1356, Emperor Charles IV issued the Golden Bull, which limited the electors to seven: the King of Bohemia, the Count Palatine of the Rhine, the Duke of Saxony, the Margrave of Brandenburg, and the archbishops of Cologne, Mainz, and Trier. During the Thirty Years' War, the Duke of Bavaria was given the right to vote as the eighth elector, and the Duke of Brunswick-Lüneburg (colloquially, Hanover) was granted a ninth electorate; additionally, the Napoleonic Wars resulted in several electorates being reallocated, but these new electors never voted before the Empire's dissolution. A candidate for election would be expected to offer concessions of land or money to the electors in order to secure their vote.

After being elected, the King of the Romans could theoretically claim the title of "Emperor" only after being crowned by the Pope. In many cases, this took several years while the King was held up by other tasks: frequently he first had to resolve conflicts in rebellious northern Italy or was quarreling with the Pope himself. Later Emperors dispensed with the papal coronation altogether, being content with the styling Emperor-Elect: the last Emperor to be crowned by the Pope was Charles V in 1530.

The Emperor had to be male and of noble blood. No law required him to be a Catholic, but as the majority of the Electors adhered to this faith, no Protestant was ever elected. Whether and to what degree he had to be German was disputed among the Electors, contemporary experts in constitutional law, and the public. During the Middle Ages, some Kings and Emperors were not of German origin, but since the Renaissance, German heritage was regarded as vital for a candidate in order to be eligible for imperial office.

The Imperial Diet (Reichstag or Reichsversammlung) was not a legislative body as is understood today, as its members envisioned it to be more like a central forum, where it was more important to negotiate than to decide. The Diet was theoretically superior to the emperor himself. It was divided into three classes. The first class, the Council of Electors, consisted of the electors, or the princes who could vote for King of the Romans. The second class, the Council of Princes, consisted of the other princes. The Council of Princes was divided into two "benches", one for secular rulers and one for ecclesiastical ones. Higher-ranking princes had individual votes, while lower-ranking princes were grouped into "colleges" by geography. Each college had one vote.

The third class was the Council of Imperial Cities, which was divided into two colleges: Swabia and the Rhine. The Council of Imperial Cities was not fully equal with the others; it could not vote on several matters such as the admission of new territories. The representation of the Free Cities at the Diet had become common since the late Middle Ages. Nevertheless, their participation was formally acknowledged only as late as 1648 with the Peace of Westphalia ending the Thirty Years' War.

The Imperial Aulic Chancellery (Reichshofkanzlei) was the main Aulic (Courtly) Chancellery of the Holy Roman Empire. It was formed in 1559, by emperor Ferdinand I, and existed until the dissolution of the Empire in 1806. During that period, it was headed by the Imperial Archchancellor (Reichserzkanzler), an honorary post traditionally reserved for the Archbishops of Mainz. In practice, it was run by the Imperial Vicechancellor (Reichsvizekanzler), who was appointed among notable statesmen and administrators in imperial service.

The Empire also had two courts: the Reichshofrat (also known in English as the Aulic Council) at the court of the King/Emperor, and the Reichskammergericht (Imperial Chamber Court), established with the Imperial Reform of 1495 by Maximilian I. The Reichskammergericht and the Aulic Council were the two highest judicial instances in the Old Empire. The Imperial Chamber court's composition was determined by both the Holy Roman Emperor and the subject states of the Empire. Within this court, the Emperor appointed the chief justice, always a highborn aristocrat, several divisional chief judges, and some of the other puisne judges.

The Aulic Council held standing over many judicial disputes of state, both in concurrence with the Imperial Chamber court and exclusively on their own. The provinces Imperial Chamber Court extended to breaches of the public peace, cases of arbitrary distraint or imprisonment, pleas which concerned the treasury, violations of the Emperor's decrees or the laws passed by the Imperial Diet, disputes about property between immediate tenants of the Empire or the subjects of different rulers, and finally suits against immediate tenants of the Empire, with the exception of criminal charges and matters relating to imperial fiefs, which went to the Aulic Council. The Aulic Council even allowed the emperors the means to depose rulers who did not live up to expectations.

As part of the Imperial Reform, six Imperial circles were established in 1500; four more were established in 1512. These were regional groupings of most (though not all) of the various states of the Empire for the purposes of defense, imperial taxation, supervision of coining, peace-keeping functions, and public security. Each circle had its own parliament, known as a Kreistag ("Circle Diet"), and one or more directors, who coordinated the affairs of the circle. Not all imperial territories were included within the imperial circles, even after 1512; the Lands of the Bohemian Crown were excluded, as were Switzerland, the imperial fiefs in northern Italy, the lands of the Imperial Knights, and certain other small territories like the Lordship of Jever.

The Army of the Holy Roman Empire (German: Reichsarmee, Reichsheer or Reichsarmatur; Latin: exercitus imperii) was created in 1422 and as a result of the Napoleonic Wars came to an end even before the Empire. It should not be confused with the Imperial Army (Kaiserliche Armee) of the Emperor.

Some constituencies of the Holy Roman Empire had additional royal or imperial territories that were, sometimes from the outset, outside the jurisdiction of the Holy Roman Empire. Henry VI, inheriting both German aspirations for imperial sovereignty and the Norman Sicilian kings' dream of hegemony in the Mediterranean, had ambitious design for a world empire. Boettcher remarks that marriage policy also played an important role here, "The marital policy of the Staufer ranged from Iberia to Russia, from Scandinavia to Sicily, from England to Byzantium and to the crusader states in the East. Henry was already casting his eyes beyond Africa and Greece, to Asia Minor and Syria and of course on Jerusalem." His annexation of Sicily changed the strategic balance in the Italian peninsula. The emperor, who wanted to make all his lands hereditary, also asserted that papal fiefs were imperial fiefs. On his death at the age of 31 though, he was unable to pass his powerful position to his son, Frederick II, who had only been elected King of the Romans. The union between Sicily and the Empire thus remained personal union. Frederick II became King of Jerusalem in 1225 through marriage to Isabella II (or Yolande) of Jerusalem and regained Bethlehem and Nazareth for the Christian side through negotiation with Al-Kamil. The Hohenstaufen dream of world empire ended with Frederick's death in 1250.

In its earlier days, the Empire provided the principal medium for Christianity to infiltrate the pagans' realms in the North and the East (Scandinavians, Magyars, Slavic people etc.). By the Reform era, the Empire, in its nature, was defensive and not aggressive, desiring of both internal peace and security against invading forces, a fact that even warlike princes such as Maximilian I appreciated. In the Early Modern age, the association with the Church (the Church Universal for the Luxemburgs, and the Catholic Church for the Habsburgs) as well as the emperor's responsibility for the defence of Central Europe remained a reality though. Even the trigger for the conception of the Imperial Reform under Sigismund was the idea of helping the Church to put its house in order.

Traditionally, German dynasties had exploited the potential of the imperial title to bring Eastern Europe into the fold, in addition to their lands north and south of the Alps. Marriage and inheritance strategies, following by (usually defensive) warfare, played a great role both for the Luxemburgs and the Habsburgs. It was under Sigismund of the Luxemburg, who married Mary, Queen regnal and the rightful heir of Hungary and later consolidated his power with the marriage to the capable and well-connected noblewoman Barbara of Cilli, that the emperor's personal empire expanded to a kingdom outside the boundary of the Holy Roman Empire: Hungary. This last monarch of the Luxemburg dynasty (who wore four royal crowns) had managed to gain an empire almost comparable in scale to the later Habsburg empire, although at the same time they lost the Kingdom of Burgundy and control over Italian territories. The Luxemburgs' focus on the East, especially Hungary, allowed the new Burgundian rulers from the Valois dynasty to foster discontent among German princes. Thus, the Habsburgs were forced to refocus their attention on the West. Frederick III's cousin and predecessor, Albert II of Germany (who was Sigismund's son-in-law and heir through his marriage with Elizabeth of Luxembourg) had managed to combine the crowns of Germany, Hungary, Bohemia and Croatia under his rule, but he died young.

During his rule, Maximilian I had a double focus on both the East and the West. The successful expansion (with the notable role of marriage policy) under Maximilian bolstered his position in the Empire, and also created more pressure for an imperial reform, so that they could get more resources and coordinated help from the German territories to defend their realms and counter hostile powers such as France. Ever since he became King of the Romans in 1486, the Empire provided essential help for his activities in Burgundian Netherlands as well as dealings with Bohemia, Hungary and other eastern polities. In the reigns of his grandsons, Croatia and the remaining rump of the Hungarian kingdom chose Ferdinand as their ruler after he managed to rescue Silesia and Bohemia from Hungary's fate against the Ottoman. Simms notes that their choice was a contractual one, tying Ferdinand's rulership in these kingdoms and territories to his election as King of the Romans and his ability to defend Central Europe. In turn, the Habsburgs' imperial rule also "depended on holding these additional extensive lands as independent sources of wealth and prestige."

The later Austrian Habsburgs from Ferdinand I were careful to maintain a distinction between their dynastic empire and the Holy Roman Empire. Peter Wilson argues that the institutions and structures developed by the Imperial Reform mostly served German lands and, although the Habsburg monarchy "remained closely entwined with the Empire", the Habsburgs deliberately refrained from including their other territories in its framework. "Instead, they developed their own institutions to manage what was, effectively, a parallel dynastic-territorial empire and which gave them an overwhelming superiority of resources, in turn allowing them to retain an almost unbroken grip on the imperial title over the next three centuries." Ferdinand had an interest in keeping Bohemia separate from imperial jurisdiction and making the connection between Bohemia and the Empire looser (Bohemia did not have to pay taxes to the Empire). As he refused the rights of an Imperial Elector as King of Bohemia (which provided him with half of his revenue), he was able to give Bohemia (as well as associated territories such as Upper and Lower Alsatia, Silesia and Moravia) the same privileged status as Austria, therefore affirming his superior position in the Empire. The Habsburgs also tried to mobilize imperial aid for Hungary (which, throughout the 16th century, cost the dynasty more money in defence expenditure than the total revenue it yielded).

Since 1542, Charles V and Ferdinand had been able to collect the Common Penny tax, or Türkenhilfe (Turkish aid), designed to protect the Empire against the Ottomans or France. But as Hungary, unlike Bohemia, was not part of the Empire, the imperial aid for Hungary depended on political factors. The obligation was only in effect if Vienna or the Empire were threatened. Wilson notes that, "In the early 1520s the Reichstag hesitated to vote aid for Hungary's King Louis II, because it regarded him as a foreign prince. This changed once Hungary passed to the Habsburgs on Louis' death in battle in 1526 and the main objective of imperial taxation across the next 90 years was to subsidize the cost of defending the Hungarian frontier against the Ottomans. The bulk of the weaponry and other military materiel was supplied by firms based in the Empire and financed by German banks. The same is true of the troops who eventually evicted the Ottomans from Hungary between 1683 and 1699. The imperial law code of 1532 was used in parts of Hungary until the mid-17th century, but otherwise Hungary had its own legal system and did not import Austrian ones. Hungarian nobles resisted the use of Germanic titles like Graf for count until 1606, and very few acquired the personal status of imperial prince."

Responding to the opinion that the Habsburg's dynastic concerns were damaging to the Holy Roman Empire, Whaley writes that, "There was no fundamental incompatibility between dynasticism and participation in the empire, either for the Habsburgs or for the Saxons or others." Imperial marriage strategies had double-edged effects for the Holy Roman Empire though. The Spanish connection was an example: while it provided a powerful partner in the defence of Christendom against the Ottomans, it allowed Charles V to transfer the Burgundian Netherlands, Franche-Comte as well as other imperial fiefs such as Milan to his son Philip II's Spanish Empire.

Other than the imperial families, other German princes possessed foreign lands as well, and foreign rulers could also acquire imperial fiefs and thus become imperial princes. This phenomenon contributed to the fragmentation of sovereignty, in which imperial vassals remained semi-sovereign, while strengthening the interconnections (and chances of mutual interference) between the Kingdom of Germany and the Empire in general with other kingdoms such as Denmark and Sweden, who accepted the status of imperial vassals on behalf of their German possessions (which were subjected to imperial laws). The two Scandinanvian monarchies honoured the obligations to come to the aid of the Empire in the wars of 17th and early 18th centuries. They also imported German princely families as rulers, although in both cases, this did not produce direct unions. Denmark consistently tried to take advantage of its influence in imperial institutions to gain new imperial fiefs along the Elbe, although these attempts generally did not succeed.