1941, the RN planned the creation and movement of the Eastern Fleet to the Indian Ocean and Singapore based on this substitution. The reinforcement of the Far East by the Eastern Fleet would occur in two phases. The first phase moved, at the earliest possible time, a minimum force into the Indian Ocean able to counter Japanese cruisers engaged in commerce raiding; the first phase would occur early in the Atlantic substitution. The second phase moved the bulk of the Eastern Fleet to Singapore or - if Singapore had fallen - the eastern Indian Ocean after American naval mobilization in the Atlantic was complete. The transfer of the Eastern Fleet was projected to be completed 80 days after the entry of the United States into the war. The basic structure of the plan remained unchanged from February 1941 to early December 1941, although the details were regularly revised. By August 1941, phase 1 was planned as Force H, joined as soon as possible by the phase 2 battleships, the and s. The limiting factor to forming the full Eastern Fleet was a shortage of cruisers and destroyers. The first British capital ships to arrive in the Indian Ocean were the battleship in mid-September, and the battlecruiser in early October. Return to offensive plans The United States did not wait to enter the war to become active in the Atlantic. By August 1941, there was sufficient American participation in the Atlantic to make a peacetime execution of the British Far East naval reinforcement plan feasible. In September, it was proposed that phase 1 could be made more powerful, and the core of the Eastern Fleet could be in place by January 1942. The shortage of destroyers would prevent the deployment of capital ships beyond the Malay Barrier, but retaining capital ships in the Indian Ocean would free cruisers to operate beyond the Malay Barrier. With such a powerful force, the RN returned to offensive plans against Japan in September. At ABC-1, the United States rejected reinforcing the United States Asiatic Fleet with a US aircraft carrier task force. The new RN plan resurrected the concept. Singapore would be the Eastern Fleet's main repair base. Manila, in the Philippines, would be its forward operating base come wartime. It would over-optimistically rely on Royal Air Force (RAF) cover in Malaya, and the major American air reinforcement of the Philippines announced at the Atlantic