Battle of the Hydaspes

In May 326 BCE, on the Hydaspes river, today's Jhelum in the Punjab province of Pakistan, Alexander the Great defeated Porus, king of the Pauravas. It was perhaps the costliest of Alexander's victories, won by a daring river crossing against a determined opponent. Alexander left Porus on his throne as a subordinate ruler, but within months his tired army refused to march further east, and the Punjab became the limit of his conquests.

By 328 BCE Alexander had destroyed the last forces loyal to the Achaemenid Empire in Central Asia. In 327 he left 10,000 men to hold Bactria and turned towards India, part of the army entering through the Khyber Pass while he took a northern route and stormed the rock fortress of Aornos. In the following spring he allied with Taxiles, also called Ambhi, king of Taxila. Taxiles' neighbour Porus refused to submit and prepared to fight. Leaving such a strong ruler untouched on his flank would have threatened Alexander's further advance and his hold on the princes who had already yielded.

Alexander camped on the north bank of the river, and Porus drew up on the south bank to stop him. The river was deep and fast, swollen by the monsoon, and a direct crossing under fire would have been suicidal. For many nights Alexander moved cavalry up and down the bank, and Porus shadowed him until he came to treat the moves as bluffs. Leaving his general Craterus at the main camp with much of the army, Alexander marched about 27 kilometres upstream to a wooded island. During a stormy night he crossed with a strong force on boats and hay-filled skin floats. Arrian, a Greek historian of the 2nd century CE, gives this force as 6,000 infantry and 5,000 cavalry, though it may have been larger. Porus sent his son with cavalry and chariots to stop the landing, but the chariots stuck in the mud, the force was routed and the son was killed.

Porus then came up with most of his army, leaving a detachment to watch Craterus. Estimates of his strength range from about 22,000 to 54,000 men, with somewhere between 85 and 200 war elephants. He placed the elephants in front of his infantry, with cavalry and chariots on the wings, and rode into battle on an elephant himself. Alexander opened with his Dahae horse archers and led the Companion cavalry against the Indian left, while Coenus took his squadrons round to strike the Indian horse from behind. The Indian cavalry broke and sheltered among the elephants.

The elephants then fell on the Macedonian phalanx and caused heavy casualties, but javelins and arrows brought down many of their drivers, and panicking animals trampled their own side. The Macedonian infantry pressed forward with locked shields while the cavalry closed in from the rear. Craterus crossed in time to lead the pursuit. Porus fought on until a friend, Meroes, persuaded him to meet Alexander.

Ancient figures disagree. Arrian lists about 310 Macedonian dead, while Diodorus gives 1,000, a figure the military historian J. F. C. Fuller thought more realistic; even that would exceed Alexander's losses at Gaugamela. Arrian puts Indian losses at 23,000; Diodorus gives 12,000 killed and more than 9,000 captured. Two of Porus' sons died, along with his relative Spitakes.

According to the famous story, Porus asked to be treated as a king, and Alexander let him keep his lands. Alexander founded two cities: Nikaia on the battlefield and Boukephala across the river, named after his horse Bucephalus, which died during or after the battle. Later that year, near the Hyphasis (the modern Beas), his men, worn out after nearly eight years of campaigning, refused to go on. Alexander turned south along the Indus instead. The strategist Kautilya, better known as Chanakya, is said to have drawn lessons from the battle about the need for trained soldiers.

Our 323 BCE map shows the Macedonian Empire at Alexander's death in 323 BCE, three years after the battle.