Philip II, b. Aug. 21, 1165, d. July 14, 1223, the son of Louis VII and Adèle of Champagne, was king of France from 1180 to 1223. Building on the work of his two predecessors (Louis VI and Louis VII), Philip made France the strongest monarchy in Europe and is usually considered to have been that country's greatest medieval king. His marriage to Isabella of Hainaut brought him the valuable land of Artois as her dowry, and his skillful use of feudal suzerainty enabled him to acquire Vermandois as well. The royal lands remained surrounded, however, by three strong feudal states—Champagne, Flanders, and the vast possessions of Henry II of England, notably Anjou and Normandy. Royal penetration of Flanders was aided when Count Baldwin IX went on the Fourth Crusade in 1202, leaving a small girl as heiress to the county. Champagne, which was ruled by Philip's maternal relatives, was usually friendly toward the French monarch. Against his main adversaries, the Plantagenet family of England, Philip followed his father's policy and supported the rebellious sons of Henry II.

On the Third Crusade (1189–91), Philip quarreled with Richard I of England, but this dangerous enemy was killed in 1199. Richard's brother, John, agreed to hold the family lands in France as Philip's vassal, but was summoned before the royal court in 1202 on the complaint of one of his own vassals. When John ignored the summons, Philip declared John's French lands forfeit and occupied (1204–06) the valuable fiefs of Normandy and Anjou. John, allied with Emperor Otto IV, attempted to regain these lands, but Philip defeated his coalition at the Battle of Bouvines in 1214. Philip was free thereafter to intervene in southern France, where the crusade against the Albigenses, which was continued by Philip's son Louis VIII and his successors, gained the French crown important lands. (Henneman, John Bell. "Philip II, King of France (Philip Augustus)." Grolier Multimedia Encyclopedia. Grolier Online, 2012. Web. 1 Feb. 2012.)