In Europe, Frederick II of Prussia failed to complete a preemptive strike against Austria, and his opponents repulsed and at Kunersdorf nearly destroyed his forces. Frederick however recovered, regained ground and managed to avoid any concessions in Hubertusburg, where the status quo ante bellum was restored. William Pitt's saying that "America was won in Germany" referred to the Prussian war effort, which enabled Great Britain to limit her continental commitments and focus on her "blue water policy," successfully establishing naval supremacy. While French and allied forces were able to occupy Prussian and Hanoverian territories up to East Frisia, French ambitions to invade Britain and to continue with their guerre de course were thwarted by a British naval blockade, which also impaired French supply routes to the colonies.