Porus or Puru raj was the King of modern day Punjab. His capital was Lahore. His kingdom lay between the Jhelum river(called Hydaspes by the Greeks) and Chenab(called Asesines in Greek literature). Alexander the great fought four battles in Asia, among which the battle of Hydases was important as he incurred heavy loses. Also, he decided to turn back and return back after this momentus battle. By the time Alexander reached the banks of Jhelum he had already conquered many big empires in Asia especially Syria, Egypt(in Africa), Persia(ruled by Darius III) and Babylonia. Alexander was 29 years old when he set out to conquer India and Porus was in his 50s.
In 327 BC Alexander and his army leave Bactria, in present day Tajakisthan and heads to Afghanistan(which was part of India then). On the way he added many Persian cavalary men to his army as they are very good at facing the elephants the Indians own in their army.In 326 BC the army of Alexander reach Indus river in Taxshashila kingdom(modern day Balochistan). The ruler of Takshashila(Taxila in Greek) is Ambhi Raj, who has enemity with Porus and Puru Kingdom. So he welcomes Alexander and joins him in his campaign to defeat Porus. He even provides him elephants, war horses and cavalary expert in warfare.
Porus is waiting for him on other end of river Hydaspes preventing him from entering North of India. Alexanders army camps on other side of Hydaspes(Jhelum) and Porus lines the other side with his army and elephants. Porus thinks that Alexander will wait for river flow to reduce to cross, but Alexander gets his men to get boats and crosses near a bent curve in river in peak summer when river is in full spate. But majority of Alexanders army is left on other side of river as this is a ambush plan. Alexanders horses are terrified of the huge elephants and refuse to swim across Jhelum. So Alexander plans to make a surprise ambush from back side on Porus army and take elephants away from the shore so that all his horses agree to land on the shore.
Alexander, in his own letters, has given as account of his war with Porus. He says the two armies were separated by the river Hydaspes, on whose opposite bank Porus continually kept his elephants in order of battle, with their heads towards their enemies, to guard the passage, that he, on the other hand, made every day a great noise and clamour in his camp, to dissipate the apprehensions of the barbarians
Alexander and his small army move in night shadows to the bent curve where his boats slowly take him to the other side. There is heavy rain the night Alexander and his small army move to other bank of Jhelum. Porus army is surprised by the early morning attack and the rain and their chariots wheel get struck in wet mud on the bank. One of Porus son dies in the attack and the remaining who are alive run off back to the main army on far shore.
Porus decides to attack Alexander himself but leaves some elephants and soldiers on bank of river to dissuade his huge army on other side from crossing over. Porus took 200-300 elephants and nearly 30000 cavalary men to attack Alexander. But by then Alexanders remaining army starts crossing the river bank. Alexander marches against left wing of Porus army and his commander Coenus marchs through the right wing. Alexanders army rains arrows on Porus army and the elephants get scared and run in panic. Coenus succeeds in breaking the right plank and moves back side and attacks Porus army from back side.
In time the elephants tired and their charges grew feebler, and with nothing worse than trumpeting. Taking his chance, Alexander surrounded the lot of them – elephants, horsemen, and all – and then signaled his infantry to lock shields and move up in a solid mass. Most of the Indian cavalry was cut down in the ensuing action; their infantry, too, hard pressed by the Macedonians, suffered terrible losses.
The Macedonians are in open field while the Porus army is struck between hills. The injured elephants go on rampage and Takshashila army and Persian cavalary dodge them. Craetrus army reach bank in teams and start attacking Porus. 20,000 infantry men of Porus are dead and 3000 cavalry men also are no more. Porus two sons die in battle. Alexander hardly loses 1000-2000 men in this battle.
Porus is brought in front of Alexander. Alexander asks what treatment he should receive. Porus replied “Treat me like a King would treat another King”. Alexander was impressed by his bravery on field and off it and made him his vassal and gave back his kingdom.
When Porus was taken prisoner, and Alexander asked him how he expected to be used, he answered, “As a king.’ For that expression, he said, when the same question was put to him a second time, comprehended everything. And Alexander, accordingly, not only suffered him to govern his own kingdom as satrap under himself, but gave him also the additional territory of various independent tribes whom he subdued…
After this battle Alexander moved towards Indian Ocean. But his beloved horse “Bucephalus” died of old age and battle wounds. Bucephalus was around thirty years old and was with Alexander since his youth. There was an rebellion in the Macedonian army and Alexander decided to go back home.
About this decision Plutarch wrote, “Alexander at first was so grieved and enraged at his men’s reluctancy that he shut himself up in his tent and threw himself upon the ground…but at last the reasonable persuasions of his friends and the cries and lamentations of his soldiers…prevailed with him to think of returning.”
But he died in 323 BC on way back home in Babylon. He probably died of malaria or liver disease by chronic drinking.