In the Crown Treaty signed on 16 November 1700, Elector Frederick III had undertaken to provide a body of 8,000 men for the impending Spanish War of Succession for Emperor Leopold I. In return, the emperor promised that Frederick's future self-coronation as "King in Prussia" would be recognised across Europe and the Holy Roman Empire. The coronation took place on 18 January 1701 in Königsberg and from April 1701 the now entitled "Royal Prussian Contingent" deployed to the Lower Rhine at Wesel. In April 1702 it took part in hostilities for the first time at the Siege of Kaiserswerth.