The reign of Philip II Augustus marked an important step in the history of French monarchy. His reign saw the French royal domain and influence greatly expanded. He set the context for the rise of power to much more powerful monarchs like Saint Louis and Philip the Fair.

Philip II spent an important part of his reign fighting the so-called Angevin Empire, which was probably the greatest threat to the King of France since the rise of the Capetian dynasty. During the first part of his reign Philip II tried using Henry II of England's son against him. He allied himself with the Duke of Aquitaine and son of Henry II – Richard Lionheart – and together they launched a decisive attack on Henry's castle and home of Chinon and removed him from power.

Richard replaced his father as King of England afterward. The two kings then went crusading during the Third Crusade; however, their alliance and friendship broke down during the crusade. The two men were once again at odds and fought each other in France until Richard was on the verge of totally defeating Philip II.

Adding to their battles in France, the Kings of France and England were trying to install their respective allies at the head of the Holy Roman Empire. If Philip II Augustus supported Philip of Swabia, member of the House of Hohenstaufen, then Richard Lionheart supported Otto IV, member of the House of Welf. Philip of Swabia had the upper hand, but his premature death made Otto IV Holy Roman Emperor. The crown of France was saved by Richard's demise after a wound he received fighting his own vassals in Limousin.

John Lackland, Richard's successor, refused to come to the French court for a trial against the Lusignans and, as Louis VI had done often to his rebellious vassals, Philip II confiscated John's possessions in France. John's defeat was swift and his attempts to reconquer his French possession at the decisive Battle of Bouvines (1214) resulted in complete failure. The annexation of Normandy and Anjou was confirmed, the Counts of Boulogne and Flanders were captured, and the Emperor Otto IV was overthrown by Philip's ally Frederick II. Aquitaine and Gascony survived the French conquest, for the Duchess Eleanor still lived. Philip II of France was crucial in ordering Western European politics in both England and France.

Prince Louis (the future Louis VIII, reigned 1223–1226) was involved in the subsequent English civil war as French and English (or rather Anglo-Norman) aristocracies were once one and were now split between allegiances. While the French kings were struggling against the Plantagenets, the Church called for the Albigensian Crusade. Southern France was then largely absorbed in the royal domains.