King Porus
Alexander had to subdue King Porus in order to keep marching east. To leave such a strong opponent at his flanks would have endangered any further exploits. Alexander could not afford to show any weakness if he wanted to keep the loyalty of the already subdued Indian princes. Porus had to defend his kingdom and chose the perfect spot to check Alexander's advance. Although he lost the battle, he became the most successful recorded opponent of Alexander. According to historian Peter Green, Porus's performance in the battle out-classed both Memnon of Rhodes and Spitamenes.