The Seven Years War and the American War of Independence were both primarily maritime struggles, but the strategic principles so successfully employed by the British in the first war were almost totally lacking in the second. The hinge of British naval strategy in the eighteenth century was the blockade of the principal fleets of France by stationing forces off Brest and Toulon. This strategy, adumbrated by Vernon and Anson, imposed by Hawke and Boscawen, and later brought to perfection by St Vincent and Cornwallis, prevented enemy fleets replenishing the French colonies overseas to any considerable degree, while at the same time it permitted the employment of conjunct operations (as they were called) for the conquest of outlying territories. When Keppel failed to force a decision off Ushant on 27 July 1778, and when Byron was dispatched too late to intercept D'Estaing's fleet from Toulon, French naval forces were not only able to co-operate with the American colonists but to appear in the Channel unopposed. Of all the leaders at that time, George Washington appears to have had the best understanding of the implications of sea-power. In his correspondence with De Grasse he frequently stresses the fact that French financial and naval aid alone enabled him to prosecute the war with success. ‘You will have observed’, he wrote after the brilliant combination of the French fleets with the American forces on land had ensured the surrender of Yorktown, ‘that what-ever efforts are made by the land armies, the navy must have the casting vote in the present contest.’