Otho had now been three years absent from Germany -three years of unwonted peace in that country—their hands had become strong. The kindred of the young Frederick became anxious for his safety. He was now about eighteen years of age. The pope was quietly consulted. He turned round, saw good reason to take active measures against Otho, and to assume the most friendly disposition towards Frederick. There were many difficulties in the way, because of the occupation of Otho; but two brave and lo,a1 Swabian knights accomplished the dangerous expedition, and Frederick was safely conducted from his sunny Palermo to the colder regions of Germany, where he was welcomed with open arms to resume his ancestral throne. But the cause of Frederick against Otho was really won by Philip Augustus of France.
Between the two rivals for the empire there was no great battle. France had all along been the steady friend of the Swabians, as England had been of the Saxons. Philip entered into a close alliance with Frederick. The Count of Flanders, the princes of the lower Rhine, and the king of England, entered into league with Otho. At the head of a large army he advanced, under the impulse of vindictive passion, towards the frontiers of France. He regarded Philip as the real author of all his misfortunes. But his vigilant adversary was ready to receive him. On the 27th of July, 1214, a great battle was fought at the village of Vouvines, not far from Lille. Philip Augustus was victorious over the last of the Othos and his allies. He survived his fall about five years, which he was allowed to spend in monastic penance without being formally deposed.
The following year Frederick II. was crowned at Aix-laChappele, and in the enthusiasm of the moment, he, with many others, made a vow to go in person on a crusade to the Holy Land. This rash promise was the occasion of troubles which he little expected, extending over his long reign of thirty-five years.