World War II Pacific: Advancing Across the Pacific

Battle of Iwo Jima

Located on the route from the Marianas to Japan, Iwo Jima provided the Japanese with airfields and an early warning station for detecting American bombing raids. Considered one of the home islands, Lt. General Tadamichi Kuribayashi prepared his defenses in depth, constructing a vast array of interlocking fortified positions connected by a large network of underground tunnels. For the Allies, Iwo Jima was desirable as an intermediate airbase as well as a staging area for the invasion of Japan.

At 2:00 AM on February 19, 1945, US ships opened fire on the island and aerial attacks began. Due to the nature of the Japanese defenses, these proved largely ineffective. The next morning, at 8:59 AM, the first landings began as the 3rd, 4th, and 5th Marine Divisions came ashore. Early resistance was light as Kuribayashi wished to hold his fire until the beaches were full of men and equipment. Over the next several days American forces advanced slowly, often under heavy machine gun and artillery fire, and captured Mount Suribachi. Able to shift troops through the tunnel network, the Japanese frequently appeared in areas that the Americans believed to be secure. Fighting on Iwo Jima proved extremely brutal as American troops gradually pushed the Japanese back. Following a final Japanese assault on March 25/26, the island was secured. In the battle, 6,821 Americans died, while 20,703 (of 21,000) Japanese were killed.

Okinawa

The final island to be taken before the proposed invasion of Japan was Okinawa. US troops began landing on April 1, 1945, and initially met light resistance as Tenth Army swept across the south-central parts of the island capturing two airfields. This early success led Lt. General Simon B. Buckner, Jr. to order the 6th Marine Division to clear the northern part of the island. This was accomplished after heavy fighting around Yae-Take.

While land forces were fighting ashore, the US fleet, supported by the British Pacific Fleet, defeated the last Japanese threat at sea. Named Operation Ten-Go, the Japanese plan called for the superbattleship Yamato and the light cruiser Yahagi to steam south on a suicide mission. The ships were to attack the US fleet and then beach themselves near Okinawa and continue the fight as shore batteries. On April 7, the ships were sighted by American scouts and Vice Admiral Marc A. Mitscher launched over 400 aircraft to intercept them. As the Japanese ships lacked air cover, the American aircraft attacked at will sinking both.

While the Japanese naval threat was removed, an aerial one remained: kamikazes. These suicide planes relentlessly attacked the Allied fleet around Okinawa, sinking numerous ships and inflicting heavy casualties. Ashore, the Allied advance was slowed by rough terrain and stiff resistance from the Japanese fortified at the southern end of the island. Fighting raged through April and May as two Japanese counteroffensives were defeated, and it was not until June 21 that resistance ended. The largest land battle of the Pacific war, Okinawa cost the Americans 12,513 killed, while the Japanese saw 66,000 soldiers die.

Ending the War

With Okinawa secured and American bombers regularly bombing and firebombing Japanese cities, planning moved forward for the invasion of Japan. Codenamed Operation Downfall, the plan called for the invasion of southern Kyushu (Operation Olympic) followed by seizing the Kanto Plain near Tokyo (Operation Coronet). Due to the geography of Japan, the Japanese high command had ascertained Allied intentions and planned their defenses accordingly. As planning moved forward, casualty estimates of 1.7 to 4 million for the invasion were presented to Secretary of War Henry Stimson. With this in mind, President Harry S. Truman authorized the use of the new atom bomb in an effort to bring a swift end to the war.

Flying from Tinian, the B-29 Enola Gay dropped the first atom bomb on Hiroshima on August 6, 1945, destroying the city. A second B-29, Bockscar, dropped a second on Nagasaki three days later. On August 8, following the Hiroshima bombing, the Soviet Union renounced its nonaggression pact with Japan and attacked into Manchuria. Facing these new threats, Japan unconditionally surrendered on August 15. On September 2, aboard the battleship USS Missouri in Tokyo Bay, the Japanese delegation formally signed the instrument of surrender ending World War II.

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