From 1209 to 1213 he resided again in the archbishopric of Cologne, where Pope Innocent III called on him to advance the cause of the Fifth Crusade. In the spring of 1214 he began to preach the crusade in the Rhineland, the Netherlands, and Friesland, where he succeeded in recruiting thousands of volunteers who pledged to take up the cross. In Cologne the crusaders began to equip their own fleet.