After a Danish occupation (1712-1715) the Duchy of Bremen was sold to the House of Hanover, and thus became ruled in personal union with the Electorate of Hanover and the Kingdom of Great Britain. In the course of the Anglo-French and Indian War (1754–63) on North American colonies "Britain" feared a French invasion in "Hanover". Thus George II Augustus formed an alliance with his Brandenburg-Prussian cousin Frederick II,"the Great" combining the North American conflict with the Austro–Brandenburg-Prussian Seven Years' War (1756–63). In summer 1757 the French invaders defeated "George II Augustus"' son William Duke of Cumberland, leading the Anglo-Hanoverian army, and drove him and his army into remote "Bremen-Verden", where in the former cloister of Zeven he had to capitulate on September 18 (Convention of Klosterzeven). But "George II Augustus" denied his recognition of the convention.