Battle of Iwo Jima - The Amphibious Landing

The Amphibious Landing

Starting on 15 June 1944, the U.S. Navy and the U.S. Army Air Forces began naval bombardments and air raids against Iwo Jima that would become the longest and most intense conflict in the Pacific theater. These would contain a combination of naval artillery shellings and aerial bombings that went on for nine months. Major General Harry Schmidt of the Marine Corps requested a ten-day heavy shelling of Iwo Jima before the amphibious assault, but was given only three days, and these were impaired by the weather conditions. Each heavy warship was given an area to fire on which combined with all the ships covered the entire island. Each warship fired for approximately six hours before stopping for a certain amount of time.

On 17 June, the destroyer escort USS Blessman sent Underwater Demolition Team 15 (UDT-15) toward Blue Beach for reconnaissance. The Japanese infantry fired on them, killing one American diver.

On the evening of 18 June, the Blessman was hit by a bomb from a Japanese warplane, killing 40 sailors, including 15 members of her UDT.

The American bombings and bombardments continued through 19 February 1945 – the day of the amphibious landing, known operationally as D-Day. The limited bombardment had questionable success on the enemy due to the Japanese being heavily dug-in and fortified. However many bunkers and caves were destroyed during the bombing giving it some limited success. The Japanese had been preparing for this battle since March 1944, which gave them a significant head start. By the time of the landing, about 450 American ships were located off Iwo Jima. The entire battle involved about 60,000 U.S. Marines and several thousand U.S. Navy Seabees.

At 08:59, one minute ahead of schedule, the first of an eventual 30,000 Marines of the 3rd Marine Division, the 4th Marine Division, and the new 5th Marine Division, making up the V Amphibious Corps, landed on the beach. The initial wave was not hit by Japanese fire for quite some time. It was the plan of General Kuribayashi to hold fire until the beach was full of the Marines and their equipment.

Many of the Marines who landed on the beach in the first wave speculated that perhaps the naval and air bombardment of the island had killed all of the Japanese troops that were expected to be defending the island. In the deathly silence, they became somewhat unnerved as Marine patrols began to advance inland in search of the Japanese positions. Only after the front wave of Marines reached a line of Japanese bunkers defended by machine gunners did they take hostile fire. Many concealed Japanese bunkers and firing positions opened up, and the first wave of Marines took devastating losses from the machine guns. Aside from the Japanese defenses situated on the beaches, the Marines faced heavy fire from Mount Suribachi at the south of the island. It was extremely difficult for the Marines to advance because of the inhospitable terrain, which consisted of volcanic ash. This ash allowed for neither a secure footing nor the construction of foxholes to protect the Marines from hostile fire. However, the ash did help to absorb some of the fragments from Japanese artillery.

The Japanese heavy artillery in Suribachi opened their reinforced steel doors to fire, and then the closed them immediately to prevent counterfire from the Marines and naval gunners. This made it difficult for American units to destroy a piece of Japanese artillery. To make matters worse for the American troops, the bunkers were connected to the elaborate tunnel system so that bunkers that were cleared with flamethrowers and grenades were reoccupied shortly afterwards by Japanese troops moving through the tunnels. This Japanese tactic caused many casualties among the Marines, as they walked past the reoccupied bunkers without expecting to suddenly take fresh fire from them. The Marines advanced slowly while taking heavy machine gun and artillery fire. With the arrival of armored tanks, and by the use of heavy naval artillery and aerial bombing on Mount Suribachi, the Marines were able to advance past the beaches. 760 Marines made a near-suicidal charge across to the other side of Iwo Jima on that first day. They took heavy casualties, but they made a considerable advance. By the evening, the mountain had been cut off from the rest of the island, and 30,000 Marines had landed. About 40,000 more would follow.

In the days after the landings, the Marines expected the usual Japanese banzai charge during the night. This had been the standard Japanese final defense strategy in previous battles against enemy ground forces in the Pacific, such as during the Battle of Saipan. In those attacks, which the Marines were prepared for, the majority of the Japanese attackers had been killed and the Japanese strength greatly reduced. However, General Kuribayashi had strictly forbidden these "human wave" attacks by the Japanese infantrymen because he considered them to be futile.

The fighting on the beachhead at Iwo Jima was very fierce. The advance of the Marines was stalled by numerous defensive positions augmented by artillery pieces. There the Marines were ambushed by Japanese troops who occasionally sprang out of tunnels. At night, the Japanese left their defenses under cover of darkness to attack American foxholes, but U.S. Navy ships fired star shells to deny them cover of darkness. Many Japanese soldiers who knew English would deliberately call for a Navy corpsman, and then shoot them as they approached. The Marines learned that firearms were relatively ineffective against the Japanese defenders and effectively used flamethrowers and grenades to flush out Japanese troops in the tunnels. One of the technological innovations of the battle, the eight Sherman M4A3R3 medium tanks equipped with a flamethrower ("Ronson" or "Zippo" tanks), proved very effective at clearing Japanese positions. The Shermans were difficult to disable, such that defenders were often compelled to assault them in the open, where the Japanese troops would fall victim to the superior numbers of Marines. Close air support (CAS) was initially provided by fighters from escort carriers off the coast. This shifted over to the 15th Fighter Group, flying P-51 Mustangs, after they arrived on the island on 6 March. Similarly, illumination rounds (flares) which were used to light up the battlefield at night were initially provided by ships, shifting over later to landing force artillery. Navajo code talkers were part of the American ground communications, along with walkie-talkies and SCR-610 backpack radio sets.

After running out of water, food, and most supplies, the Japanese troops became desperate towards the end of the battle. Kuribayashi, who had argued against banzai attacks at the start of the battle, realized that Japanese defeat was imminent. Marines began to face increasing numbers of nighttime attacks; these were only repelled by a combination of machine gun defensive positions and artillery support. At times, the Marines engaged in hand-to-hand fighting to repel the Japanese attacks. With the landing area secure, more troops and heavy equipment came ashore and the invasion proceeded north to capture the airfields and the remainder of the island. Most Japanese soldiers fought to the death.