Why did Richard I fight Philip II of France after returning from captivity?

Richard I fought Philip II of France upon his return from captivity primarily because Philip had violated his promises and exploited Richard's absence to attack the Plantagenet possessions in France.1

While both kings had participated in the Third Crusade, Philip returned to France early in 1191, ostensibly due to illness, but with the clear intention of expanding his own domains while Richard was still away. During Richard's subsequent imprisonment by Leopold V, Philip actively worked to prolong his rival's captivity. Once Richard was released in 1194, he immediately went to war against Philip to reclaim his territories and defend his interests against the French king's aggression.1