Yahara was the senior staff officer in charge of operations of the 32nd Japanese Army at Okinawa during the American invasion of that island during World War II. Yahara, who had taught strategy at the Army War College, was assigned to Okinawa prior to the anticipated American invasion to organize its pre-invasion strategy. His recommended strategy for fighting the American invaders was to continue to tie up the American military as long as possible in a war of attrition (jikyusen), so that the rumored American invasion of Kyūshū, Japan, would be delayed, thereby allowing Kyushu defenders more time to better prepare their defenses. Once the Okinawa invasion started, Yahara recommended holding back Japanese forces for as long as possible and using them primarily in a defensive posture, rather than an aggressive one. However, Chief of Staff of the Army, Lieutenant General Isamu Cho, soon became frustrated by the relative inaction of the battlefield, and recommended "banzai" charges at the Americans. Yahara disagreed with this recommendation, but went along with it. But when it was clear that Cho's samurai-charge methods were not working, but, rather, causing huge numbers of casualties among the Japanese infantry, along with loss of territory, Cho relented and allowed Yahara to continue to make tactical and operational decisions. Yahara's methods, since he did not have the firepower to fight the Americans directly in battle and knew that he could not possibly win, was to fight from caves as long as possible, and then, once the caves were lost, to "retreat and defend" -- time after time—until there was no longer any room to retreat to. Lieutenant General Cho and Lieutenant General Mitsuru Ushijima, ordered Yahara to escape from the Mabuni caves after they had committed ritualistic suicide, despite Yahara's pleas to committ seppuku alongside the two generals. This he did, disguised as a Japanese English teacher. This disguise worked well for him on the island, but eventually he was recognized by the U.S. military and made a prisoner-of-war with privileges due his rank. After the war, Yahara wrote his account of the battle. His "Okinawa Kessen" (Battle for Okinawa), first published in Japanese in 1973, was an account of his first-hand experience directing Japanese operations on Okinawa during the invasion. He died in 1981.