The main general for the United States in the Pacific theater during World War II was Douglas MacArthur. MacArthur had a great number of successes and eventually accepted a surrender from Japan, but his time during World War II was not without its losses and failures.
Japan's first attack on MacArthur's troops in the Philippines was a surprise and caused the American forces to suffer many losses. The general was forced to retreat to Australia for a time. After this attack, he was giving the command of all the Allied forces in the Pacific. The next couple of years saw many wins as the Allied forces moved from island to island, until returning to the Philippines in 1944 where they defeated the Japanese forces. Japan officially surrendered in 1945.