Despite close surveillance by the Pauravas, Alexander's decision to cross the monsoon-swollen Hydaspes to catch Porus' army in the flank has been called one of his "masterpieces" in combat.

[23] The Hyphasis marked the farthest advance of Alexander in India, and upon leaving, he "left King Porus in charge of this easternmost territory.

[24] Whilst possessing a much larger army, at the battle, an estimated 40,000 infantry and 5,000 cavalry crossed the river in time to engage the enemy.

[25] In early spring of the next year, Alexander formed an alliance with Taxiles (local name Ambhi), the King of Taxila.

They combined their forces against Taxiles' neighbour, the King of Hydaspes, Porus the Elder, who had chosen to spurn Alexander's command for him to surrender and was preparing for war.

[citation needed] The other forces commanded by Meleager, Attalus, and Gorgias were ordered to cross the river in various places during the manoeuvre.

Alexander quietly moved his part of the army upstream and then traversed the river in utmost secrecy, using 'skin floats filled with hay' as well as 'smaller vessels cut in half, the thirty oared galleys into three'.

Having crossed the river, Alexander advanced towards the location of Porus' camp with all his horsemen and foot archers, leaving his phalanx to follow up behind.

[31] Upon meeting with young Porus' force, his horse archers showered the latter with arrows, while his heavy cavalry immediately charged without forming into line of battle.

The Indian war elephants were heavily armoured and had castle-like howdahs on their back carrying a trio of archers and javelin men.

Porus' soldiers were dressed in flamboyantly hued outfits with steel helmets, bright scarves and baldrics, and wielded axes, lances and maces.

Porus, eschewing the usual tradition of Indian kings fighting from a chariot, was mounted atop his tallest war elephant.

[12] His armoured Companion cavalry was sent to attack their outnumbered Indian counterparts on the left wing, with Alexander himself leading the charge as was his habit.

[33] The rest of the Indian cavalry galloped to the aid of their hard-pressed kinsmen from the right wing, but Coenus's squadrons promptly followed their movement and attacked them from the rear.

The Indian horsemen tried to form a double phalanx to face both attacks, but the necessary complicated manoeuvres brought even more confusion into their ranks, making it easier for the Macedonian cavalry to defeat them.

The powerful beasts caused heavy losses among the Macedonian foot, impaling many men with their steel-clad tusks and heaving some of them into the air before pulverizing them, and trampling and disorganizing their dense lines.

Many of their mahouts had been struck down by Macedonian missiles before they could kill their panicked mounts with poisoned rods, and hence the maddened animals wrought enormous havoc, trampling many of their own infantry and cavalry to death.

[36] Meanwhile, Craterus and his force in the base camp had succeeded in crossing the river, and arriving just at the right moment proceed to conduct a thorough pursuit on the fleeing Indians.

Hoping to save the life of such a competent leader and warrior, Alexander commanded Taxiles to summon Porus for surrender.

[14][42] This was certainly a high figure for the victorious army, and more than the Macedonian losses at Gaugamela, yet not improbable considering the partial success of the Indian war elephants.

[46][42] Alexander also acquired an additional 70 war elephants due to the late arrival of reinforcements called for by King Porus after the battle was already over, who readily surrendered and offered these beasts as a tribute.

[24] Instead of immediately turning back, however, he ordered the army to march south, along the Indus, securing the banks of the river as the borders of his empire.