Philip II, known as Philip Augustus, consolidated Capetian power through territorial conquest, alliances and administrative reform. Crowned during his father Louis VII's lifetime in 1179, he became sole king in 1180. Early struggles with great nobles secured gains including interests in Artois, Amiens and Vermandois. He then concentrated on the Plantagenet rulers of England, whose extensive French territories posed the greatest challenge to royal authority.

Philip supported Henry II's rebellious sons and later joined Richard I in the Third Crusade. He participated in the siege of Acre in 1191 but returned to France before Richard, renewing their rivalry over continental possessions. Richard's captivity and subsequent release created further opportunities and reversals. Philip's success became more decisive after Richard's death in 1199, when King John faced disputes with his French vassals.

Using complaints against John and a judgment of forfeiture, Philip invaded Plantagenet lands. The fall of Château Gaillard in 1204 opened the way to the conquest of Normandy, followed by other major gains in western France. In 1214 he defeated the coalition led by Emperor Otto IV at Bouvines, while his son Louis checked John's advance elsewhere. These victories secured much of the territorial transformation and strengthened the standing of the monarchy among its subjects and rivals.

Philip supported more regular royal administration through officials such as baillis and expanded the resources available to the crown. In Paris he sponsored fortifications, the Louvre fortress and improvements to streets and markets. His reign also included coercive policies toward Jews, including expulsion and confiscation early in his rule, followed by a later permitted return. Disputes over his marriages brought conflict with the papacy. By his death in 1223 the royal domain was greatly enlarged and the monarchy better equipped to govern it.