12 days after she was completed and commissioned, Kongō departed from Portsmouth to Japan. She was placed in the first reserve. When Japan declared war Germany on 23rd August 1914, Kongō was deployed to patrol along the sea lines of communication of the German empire. In october, Kongō and her sister ship Hiei sortied off the Chinese coast to support the Japanese army during the siege of Tsingtao. After the Battle of the Falkland Islands, there was little need for IJN operations in the Pacific as Germany forces was defeated by the Royal Navy. Kongō spent the rest of WW I at sasebo or on patrol off the coast of China. After the war, Kongō was placed in the second reserve.
On 1st December 1931, 2 months after Japan invaded Manchuria, Kongō was assigned to the First Battleship Division and designated the Flagship of the Combined Fleet. After intensive modifications, Kongō was reclassified as a Fast Battleship.
On 29th November 1941, Kongō and her sister ship Haruna departed from Hashirajima fleet anchorage to begin the Pacific War as part of the Southern Force's main body. When the Prince of Wales and Repulse was sunk by Japanese aircrafts, Kongō's battle group withdrew from Malayan waters. During the Battle of Midway, Kongō and Hiei sortied with 5 Heavy cruisers as part of Admiral Nobutake Kondō's invasion force. Following the loss of Aircraft Carriers Akagi, Kaga, Souryuu and Hiryuu, the force withdrew to Japan. To protect Japan's transports from enemy air attacks, Admiral Isoroku Yamamoto sent Kongō and Haruna escorted by a light cruiser and 9 destroyers to bombard American air base at Henderson Field. On 15th November, after Hiei and Kirishima was sunk during the Battle of Guadalcanal, the Third Battleship Division returned to Truk and saw no major combat action until 1944.
To be continued in next post.