Completed in 1920 as the lead ship of her class, she carried supplies for the survivors of the Great Kantō earthquake in 1923. The ship was modernized in 1934–1936 with improvements to her armor and machinery and a rebuilt superstructure in the pagoda mast style. Nagato briefly participated in the Second Sino-Japanese War in 1937 and was the flagship of Admiral Isoroku Yamamoto during the attack on Pearl Harbor.