In the summer of 1757, the French invaded Hanover and defeated George II's son Prince William, Duke of Cumberland, leading the Anglo-Hanoverian army, at the Battle of Hastenbeck and drove him and his army into remote Bremen-Verden, where in the former "Zeven" he capitulated on 18 September (Convention of Kloster-Zeven). But George II did not recognise the convention. In the following year the British army, supported by troops from Brandenburg-Prussia, Hesse-Kassel and the ducal Principality of Brunswick and Lunenburg (Wolfenbüttel) again expelled the occupants.