Britain's carriers during 1942 were split between the Atlantic and Pacific theaters. Four of her eight carriers were in the Indian Ocean at the time of Japan's Indian Ocean raid in April. Japan's successful raid resulted in the British withdrawing her naval base from Ceylon to East Africa and in the loss of the light carrier HMS "Hermes". Fleet carriers HMS "Illustrious", "Formidable", and "Indomitable" provided air cover for the British assault on Vichy French forces at Madagascar. However, all British carriers were moved to the Atlantic Ocean or Mediterranean Sea by January 1943 and did not return to engage against the Japanese in the Pacific until mid-1944.