chief gunnery officer to the destroyer on 1 December 1919 before returning to Kongō on 1 December 1921 as secondary gunnery officer. During his tour aboard her, Kongō operated off Dairen and Tsingtao, China, and St. Vladimir Bay, Russia, and visited Chinhae, Korea. On 1 December 1922, Ugaki entered the Japanese . In 1924, he graduated in its 22nd class, and on 1 December 1924 he was promoted to lieutenant commander and began a stint as gunnery officer aboard the light cruiser . On 1 December 1925, he became a staff officer on the Imperial Japanese Navy General Staff and served for nearly three years as a staff member of the Naval Gunnery School. On 15 November 1928 he was appointed as a resident officer in Germany, and he was promoted to commander on 10 December 1928. Ordered back to Japan on 1 November 1930, Ugaki returned to sea in an assignment as a staff officer in the 3rd Cruiser Division on 1 December 1930, and then became a staff officer in the 2nd Fleet on 1 December 1931. Ugaki became an instructor at the Naval War College on 15 November 1932 and received a promotion to captain on 1 December 1932. On 30 October 1935, Ugaki was assigned to duty as a staff officer to the Combined Fleet, then received his first command on 1 December 1936 as commanding officer of the training ship , From 7 June to 19 October 1937, Yakumo made a training cruise to Suez and the Mediterranean under his command with the 64th class of the Japanese Naval Academy embarked. On 1 December 1937, he took command of the battleship , which operated as part of the Japanese blockade of the southern coast of China during the Second Sino-Japanese War. Ugaki was promoted to rear admiral on 15 November 1938 and became Director, 1st Bureau (Operations) on the Naval General Staff on 15 December 1938. He took command of the 8th Cruiser Division, consisting of the heavy cruisers and , on 10 April 1941. In August 1941, Ugaki was appointed Chief-of-Staff of the Combined Fleet under Admiral Isoroku Yamamoto, a position he held until Yamamoto's death. World War II The Pacific campaign of World War II began with the Japanese attack on Pearl Harbor, Hawaii, on 7 December 1941 (8 December 1941 on the other side of the International Date Line in Japan), and