On May 2, 1945, he was assigned to a rifle company of the 5th Marines during the invasion of Okinawa. That day, the 5th Marines were pushing uphill towards a ridge against determined Japanese resistance. The slope was strewn with Marine casualties, and Corpsman Bush moved unceasingly among them rendering aid despite the withering fire all around him.
When the attack passed over the crest of the ridge, he moved up to the top of the slope to aid a wounded Marine officer. A Japanese counterattack swept over the ridge just as he began administering blood plasma to his patient.
As the Japanese approached, Corpsman Bush gallantly held up the plasma bottle with one hand and fired a pistol at the Japanese with the other. Then he grabbed a carbine and killed six advancing Japanese. He suffered several serious wounds himself, including the loss of an eye.
He remained guarding his “officer patient” until the enemy were repulsed. Then, according to the official citation, he “valiantly refus[ed] medical treatment for himself until his officer patient had been evacuated…”