Many of the magnates had absented themselves from the diet at Muehlhausen, and an irreconcilable band of partisans refused to be bound by its decisions.  Richard of England now worked actively for Otto, his favorite nephew, and found support both in the old allies of the Angevins in the Lower Rhineland and the ancient supporters of the house of Guelf.  Germany was thus divided into two parties, who completely ignored each other’s acts.  Three months after the diet of Muehlhausen, another diet met at Cologne and chose Otto of Brunswick as King of the Romans.  Three days afterward the young prince was crowned at Aachen.

A ten-years’ civil war between Philip II and Otto IV now devastated the Germany that Barbarossa and Henry VI had left so prosperous.  The majority of the princes remained firm to Philip, who also had the support of the strong and homogeneous official class of ministeriales that had been the best helpers of his father and brother.  Nevertheless, Otto had enough of a party to carry on the struggle.  On his side was Cologne, the great mart of Lower Germany, so important from its close trading relations with England, and now gradually shaking itself free of its archbishops.  The friendship of Canute of Denmark and the Guelf tradition combined to give him his earliest and greatest success in the North.  It was the interest of the baronage to prolong a struggle which secured their own independence at the expense of the central authority.  Both parties looked for outside help.  Otto, besides his Danish friends, relied on his uncle Richard, and, after his death, on his uncle John.  Philip formed a league with his namesake Philip of France.  But distant princes could do but little to determine the result of the contest.  It was of more moment that both appealed to Innocent III, and that the Pope willingly accepted the position of arbiter.  “The settlement of this matter,” he declared, “belongs to the apostolic see, mainly because it was the apostolic see that transferred the Empire from the East to the West, and ultimately because the same see confers the Imperial crown.”

In March, 1201, Innocent issued his decision.  “We pronounce,” he declared, “Philip unworthy of empire, and absolve all who have taken oaths of fealty to him as king.  Inasmuch as our dearest son in Christ, Otto, is industrious, discreet, strong, and constant, himself devoted to the Church and descended on each side from a devout stock, we, by the authority of St. Peter, receive him as king, and will in due course bestow upon him the imperial crown.”  The grateful Otto promised in return to maintain all the possessions and privileges of the Roman Church, including the inheritance of the countess Matilda.