Isabelle, Philip's first wife
Philip was born in Gonesse on 21 August 1165. King Louis VII intended to make his son Philip co-ruler with him as soon as possible, in accordance with the traditions of the House of Capet, but these plans were delayed when Philip, at the age of thirteen, was separated from his companions during a royal hunt and became lost in the Forest of Compiègne. He spent much of the following night attempting to find his way out, but to no avail. Exhausted by cold, hunger and fatigue, he was eventually discovered by a peasant carrying a charcoal burner, but his exposure to the elements meant he soon contracted a dangerously high fever. His father went on pilgrimage to the Shrine of Thomas Becket to pray for Philip's recovery and was told that his son had indeed recovered. However, on his way back to Paris, the king suffered a stroke.
In declining health, Louis VII had his 14-year-old son crowned and anointed as king at Reims on 1 November 1179 by Archbishop William of the White Hands. He was married on 28 April 1180 to Isabelle of Hainaut, the daughter of Baldwin V, Count of Hainaut, and Margaret I, Countess of Flanders, who brought the County of Artois as her dowry. From the time of his coronation, all real power was transferred to Philip, as his father slowly descended into senility. The great nobles were discontented with Philip's advantageous marriage, while his mother and four uncles, all of whom exercised enormous influence over Louis, were extremely unhappy with his attainment of the throne, which caused a diminution of their power. Eventually, Louis died on 18 September 1180.
Consolidation of the royal demesne
The coronation of Philip II Augustus in the presence of Henry II of England
While the royal demesne had increased under Philip I and Louis VI, it had diminished slightly under Louis VII. In April 1182, partially to enrich the French crown, Philip expelled all Jews from the demesne and confiscated their goods. Philip's eldest son Louis was born on 5 September 1187 and inherited the County of Artois in 1190, when his mother Isabelle died. The main source of funding for Philip's army was from the royal demesne. In times of conflict, he could immediately call up 250 knights, 250 horse sergeants, 100 mounted crossbowmen, 133 crossbowmen on foot, 2,000 foot sergeants, and 300 mercenaries. Towards the end of his reign, the king could muster some 3,000 knights, 9,000 sergeants, 6,000 urban militiamen, and thousands of foot sergeants. Using his increased revenues, Philip was the first Capetian king to build a French navy actively. By 1215, his fleet could carry a total of 7,000 men. Within two years, his fleet included 10 large ships and many smaller ones.
Wars with his vassals
In 1181, Philip began a war with Philip, Count of Flanders, over the Vermandois, which King Philip claimed as his wife's dowry and the Count was unwilling to give up. Finally the Count of Flanders invaded France, ravaging the whole district between the Somme and the Oise before penetrating as far as Dammartin. Notified of Philip's impending approach with 2,000 knights, he turned around and headed back to Flanders. Philip chased him, and the two armies confronted each other near Amiens. By this stage, Philip had managed to counter the ambitions of the count by breaking his alliances with Henry I, Duke of Brabant, and Philip of Heinsberg, Archbishop of Cologne. This, together with an uncertain outcome were he to engage the French in battle, forced the Count to conclude a peace. In July 1185, the Treaty of Boves left the disputed territory partitioned, with Amiénois, Artois, and numerous other places passing to the king, and the remainder, with the county of Vermandois proper, left provisionally to the Count of Flanders. It was during this time that Philip II was nicknamed "Augustus" by the monk Rigord for augmenting French lands.
Meanwhile, in 1184, Stephen I, Count of Sancerre and his Brabançon mercenaries ravaged the Orléanais. Philip defeated him with the aid of the Confrères de la Paix.
War with Henry II
Philip also began to wage war with King Henry II of England, who was also Count of Anjou and Duke of Normandy and Aquitaine in France. The death of Henry's eldest son, Henry the Young King, in June 1183, began a dispute over the dowry of Philip's widowed sister Margaret. Philip insisted that the dowry should be returned to France as the marriage did not produce any children, per the betrothal agreement. The two kings would hold conferences at the foot of an elm tree near Gisors, which was so positioned that it would overshadow each monarch's territory, but to no avail. Philip pushed the case further when King Béla III of Hungary asked for the widow's hand in marriage, and thus her dowry had to be returned, to which Henry finally agreed.
Remains of the Wall of Philip II Augustus
built around Paris before he went to the Crusades. The segment pictured here is found in the Rue des Jardins-Saint-Paul, Paris.
The death in 1186 of Henry's fourth son, Geoffrey II, Duke of Brittany, began a new round of disputes, as Henry insisted that he retain the guardianship of the duchy for his unborn grandson Arthur I, Duke of Brittany. Philip, as Henry's liege lord, objected, stating that he should be the rightful guardian until the birth of the child. Philip then raised the issue of his other sister, Alys, Countess of Vexin, and her delayed betrothal to Henry's son Richard I of England, nicknamed Richard the Lionheart.
With these grievances, two years of combat followed (1186–1188), but the situation remained unchanged. Philip initially allied with Henry's young sons Richard the Lionheart and John Lackland, who were in rebellion against their father. Philip II launched an attack on Berry in the summer of 1187, but in June made a truce with Henry, which left Issoudun in his hands and also granted him Fréteval in Vendômois. Though the truce was for two years, Philip found grounds for resuming hostilities in the summer of 1188. He skilfully exploited the estrangement between Henry and Richard, and Richard did homage to him voluntarily at Bonsmoulins in November 1188.
In 1189, Richard openly joined forces with Philip to drive Henry into abject submission. They chased him from Le Mans to Saumur, losing Tours in the process, before forcing him to acknowledge Richard as his heir. Finally, by the Treaty of Azay-le-Rideau (4 July 1189), Henry was forced to renew his own homage, confirm the cession of Issoudun to Philip (along with Graçay), and renounce his claim to suzerainty over Auvergne. Henry died two days later. His death, and the news of the fall of Jerusalem to Saladin, diverted attention from the Franco-English war.
The Angevin kings of England (the line of rulers to which Henry II belonged), were Philip's most powerful and dangerous vassals as Dukes of Normandy and Aquitaine and Counts of Anjou. Philip made it his life's work to destroy Angevin power in France. One of his most effective tools was to befriend all of Henry's sons and use them to foment rebellion against their father. He maintained friendships with Henry the Young King and Geoffrey II until their deaths. Indeed, at the funeral of Geoffrey, he was so overcome with grief that he had to be forcibly restrained from casting himself into the grave. He broke off his friendships with Henry's younger sons Richard and John as each acceded to the English throne.