During the attempted coup by a faction of the Imperial Japanese Army in February 1936 (the February 26 incident, Ōsumi's actions were remarkably ambiguous. Although the commander of the Combined Fleet, Admiral Sankichi Takahashi ordered his battleships in Tokyo Bay and targeted the rebel positions, and the commander of the Yokosuka Naval District, Admiral Shigeyoshi Inoue organized a land force to march on Tokyo, Ōsumi refused to issue any orders or take any action, despite word that Prime Minister Okada Keisuke had survived the attack. After the suppression of the coup, Ōsumi resigned as Minister of the Navy, and served as Naval Councilor from 1936 onwards. In 1940, on the retirement of Prince Fushimi Hiroyasu, Ōsumi became the most senior admiral in the Imperial Japanese Navy; however, he was bypassed for promotion by Osami Nagano.