Germany during the Crusades
Contending Kings
Philip VI
The electors of Germany quickly chose Philip of Swabia, Henry VI's brother, as their new emperor. The Archbishop of Cologne, however, was an old enemy and wanted to put an end to Hohenstaufen rule, so he put forward another candidate: Otto, the third son of Duke Henry the Lion, the great Welf rival of Emperor Frederick I. The Archbishop had the backing of at least some northern barons, and more importantly had the support of the English. Otto was living in England at the time, and England had been a long-time supporter of the Welfs ever since Henry the Lion had been an exile there.
With two kings in Germany, war was inevitable. Philip was victorious in the field, and in 1206 forced Otto to more or less retire to his estates in Brunswick. Pope Innocent III, who had been supporting Otto, now withdrew that support. It looked like Philip would be King of Germany, at least until the child Frederick, who was living in Palermo, reached adulthood.
This all changed on 8 June 1208, however, when Philip was assassinated due to a private quarrel. By the end of the year, Otto of Brunswick was recognized by all the German princes and was crowned emperor (in 1209) as Otto IV.
Otto IV
Otto was never up to the job, though. He did the right things, but always seemed to do them badly or at the wrong time.
For example, he had promised Innocent that he would respect papal claims in Italy, but after being crowned he immediately moved on the Kingdom of Italy to reassert imperial authority there. The civil war in Germany had allowed the Italian cities to become nearly independent, and no emperor could allow that. For his trouble, he found himself excommunicated by Pope Innocent in 1210.
The following year Otto invaded Sicily (which had naturally tried to break away from imperial control). Although he was not defeated there, he had to leave almost at once because the Staufen princes in Germany took the occasion to elect a new emperor.
What new emperor? The young Frederick of Hohenstaufen, who had slipped out of Sicily in the fall of 1211 and gone north with almost no supporters, to claim his father's titles.
Otto returned to Germany in 1212, but was not strong enough to oppose the Staufen. He was defeated at Bouvines in 1214 and had to retreat again to his estates in Brunswick. He spent four years there, watching his support go over to Frederick, and was finally murdered at his Harzburg Castle in 1218.