Emperor Otto IV acknowledged him as count of Holland in 1203 because he was a supporter of the
Welfs. He and many others changed allegiance to
Frederick II after the
battle of Bouvines in 1214. He took part in a French expedition against
King John of England. The
pope excommunicated him for this. Possibly because of this, William then became a fervent crusader and by this his excommunication was lifted. He campaigned in
Prussia. In Europe, he came to be called William
the Crazy for his chivalric and reckless behaviour in battle. On his way to the Egypt, he commanded a joined force of Frisian, Dutch, Flemish and Rhenish crusaders that helped the Portuguese
conquered the city of Alcácer do Sal from the
Almohads as it is noted in the
De itinere Frisonum and the
Gesta crucigerorum Rhenanorum. William helped to conquer the city of
Damietta during the
Fifth Crusade. There were great changes in the landscape of
Holland in the end of the 12th and during the 13th century. Many colonists bought land to turn the swamps into
polders. Most of the swamps had been sold, and irrigation had started during the reign of William. Huge infrastructural works were done; the island called
Grote Waard was enclosed with dikes all around and a dam was built at
Spaarndam. New governmental bodies were created, the so-called
water boards, which were charged with the task of protecting the polders against ever-present threat of flooding. Count William granted city rights to
Geertruidenberg in 1213, to
Dordrecht in 1217, to
Middelburg in 1220 and perhaps also to
Leiden. In this way he gave an impulse to trade. ==Family==