 The expedition was planned by the administration of Robert Harley, chief minister of the crown, and was based on plans originally proposed in 1708.Harley decided to mount the expedition as part of a major shift in British military policy, emphasizing strength at sea.The expedition's leaders, Admiral Hovenden Walker and Brigadier-General John Hill, were chosen for their politics and connections to the crown, and its plans were kept secret even from the Admiralty.