These rapid changes could not take place without exciting the anxious attention of the king of England. His family interests, possibly also his prestige on the continent, had suffered to some extent in the complete overthrow and exile of his son-in-law Henry the Lion by the Emperor Frederick I, which had occurred in January, 1180, a few weeks before the marriage of Philip II, though as yet the Emperor had not been able to enforce the decision of the diet against the powerful duke. Henry of England would have been glad to aid his son-in-law with a strong force against the designs of Frederick, which threatened the revival of the imperial power and might be dangerous to all the sovereigns of the west if they succeeded, but he found himself between somewhat conflicting interests and unable to declare himself with decision for either without the risk of sacrificing the other. Already, before Philip's marriage, the young Henry had gone over to England to give his father an account of the situation in France, and together they had crossed to Normandy early in April. But the marriage had taken place a little later, and May 29 Philip and his bride were crowned at St. Denis by the Archbishop of Sens, an intentional slight to William of Blois, the Archbishop of Reims. Troops were called into the field on both sides and preparations made for war, while the house of Blois formed a close alliance with Henry. But the grandson of the great negotiator, Henry I, had no intention of appealing to the sword until he had tried the effect of diplomacy. On June 28 Henry and Philip met at Gisors under the old elm tree which had witnessed so many personal interviews between the kings of England and France. Here Henry won another success. Philip was reconciled with his mother's family; an end was brought to the exclusive influence of the Count of Flanders; and a treaty of peace and friendship was drawn up between the two kings modelled closely on that lately made between Henry and Louis VII, but containing only a general reference to a crusade. Henceforth, for a time, the character of Henry exercised a strong influence over the young king of France, and his practical statesmanship became a model for Philip's imitation.