a Japanese one of similar size. Following its debut at Pearl Harbor, the Kido Butai supported the capture of Rabaul in January 1942 and the Dutch East Indies in February. The only problem encountered by the Japanese during the First Operational Phase was the failure to occupy the Philippines on schedule. However, with no expectation of reinforcement, the fall of the Philippines was only a matter of time and the remaining American and Filipino forces surrendered in early May 1942. Indian Ocean raid The last major operation of the First Operational Phase was the Combined Fleet's raid into the Indian Ocean, code-named Operation C, it was essential for the completion of the defensive perimeter. This significant operation included five carriers to neutralize the Royal Navy's Eastern Fleet with an attack on Ceylon, the heart of British naval power in the East, and a task force built around heavy cruisers to attack shipping in the Bay of Bengal. The operation began in April with the Japanese delivering heavy attacks against British bases at Colombo and Trincomalee. Japanese carrier aircraft also caught and sank a light carrier HMS Hermes and the two heavy cruisers HMS Dorsetshire and HMS Cornwall, but were unable to locate and destroy the main British fleet. The Japanese cruiser raiding force wreaked havoc with British shipping in the Bay of Bengal, from April 4 to 9, the Japanese sank 23 merchant ships totaling 32,404 tons. However, the entire operation was a strategic dead end since it was only a temporary projection of power that could not be sustained and served only to put more strain on the Japanese carrier force. Strategic setbacks (1942) The ease with which the Japanese accomplished their initial objectives led to the severe underestimation of the enemy and the resultant failure to concentrate the IJN's superior forces at key places and times. As a result, the critical months of May and June 1942 saw the IJN lose both its offensive power and the initiative. The Second Operational Phase was planned to expand Japan's strategic depth by adding eastern New Guinea, New Britain, the Aleutians, Midway, the Fiji Islands, Samoa, and strategic points in the Australian area. However, the Naval General Staff, the Combined Fleet, and the Imperial Army, all had different views on the next sequence of operations. The Naval General Staff advocated an advance to the south to seize parts of Australia, however,