North deferred overall strategy of the war to his key subordinates Lord George Germain and the Earl of Sandwich. Despite a series of victories and the capture of New York and Philadelphia, the British were unable to secure a decisive victory. In 1778, the French allied themselves with the American rebels, and Spain joined the war in 1779 as an ally of France, followed by the Dutch Republic in 1780. The British found themselves fighting a global war on four continents without a single ally. After 1778, the British switched the focus of their efforts to the defence of the West Indies, as their sugar wealth made them much more valuable to Great Britain than the Thirteen Colonies. In 1779, Great Britain was faced with the prospect of a major Franco-Spanish invasion, but the Armada of 1779 was ultimately a failure. Several peace initiatives fell through, and an attempt by Richard Cumberland to negotiate a separate peace with Spain ended in frustration.