After the Meiji Restoration, Ogawa attended the Imperial Japanese Army Academy and was commissioned as a second lieutenant in January 1871 and promoted to lieutenant in February 1874. He participated in the Taiwan Expedition of April 1874. Afterwards, he served with the IJA 1st Infantry Regiment under the Tokyo Garrison, and as a battalion commander with the IJA 13th Infantry Regiment from April 1876. From February 1877, he fought in the Satsuma Rebellion, but was wounded in combat in April and promoted to major the same month.