Despite a successful campaign with their Austrian allies, the defeat of the latter at the Battle of Wagram on 6 July 1809 led to the Armistice of Znaim on 12 July. William refused to accept this and led his "Schwarze Schar" ("Black Host") into Germany, succeeding in briefly taking control of the city of Brunswick. Faced with superior Westphalian forces, the Brunswickers conducted a remarkable fighting retreat across Germany, twice holding off the pursuing armies, at the Battle of Halberstadt and the Battle of Ölper; finally being evacuated by the Royal Navy from the mouth of the River Weser. Landing in England, the Duke was welcomed by his cousin and brother-in-law, the Prince Regent (later King George IV) and the Black Brunswickers entered British service. During the next few years, the Brunswickers earned themselves a sound reputation through service with the British in the Peninsular Campaign. However, steady attrition in battles and skirmishes through Portugal and Spain, combined with a lack of political support and financial difficulties, led to a situation where the unit's imminent disbandment looked likely.