Commemoration of the Battle of Iwo Jima

Commemoration of the Battle of Iwo Jima
(February 19, 1945 – March 26, 1945)

(source: Wikipedia) The Battle of Iwo Jima (19 February – 26 March 1945) was a major battle in which the United States Marine Corps and Navy landed on and eventually captured the island of Iwo Jima from the Imperial Japanese Army (IJA) during World War II. The American invasion, designated Operation Detachment, had the goal of capturing the entire island, including the three Japanese-controlled airfields (including the South Field and the Central Field), to provide a staging area for attacks on the Japanese main islands. This five-week battle comprised some of the fiercest and bloodiest fighting of the Pacific War of World War II.

After the heavy losses incurred in the battle, the strategic value of the island became controversial. It was useless to the U.S. Army as a staging base and useless to the U.S. Navy as a fleet base. However, Navy Seabees rebuilt the landing strips, which were used as emergency landing strips for USAAF B-29s.

The IJA positions on the island were heavily fortified, with a dense network of bunkers, hidden artillery positions, and 18 km (11 mi) of tunnels. The American ground forces were supported by extensive naval artillery, and had complete air supremacy provided by U.S. Navy and Marine Corps aviators throughout the battle.

Japanese combat deaths numbered three times the number of American deaths although, uniquely among Pacific War Marine battles, American total casualties (dead and wounded) exceeded those of the Japanese. Of the 21,000 Japanese soldiers on Iwo Jima at the beginning of the battle, only 216 were taken prisoner, some of whom were captured because they had been knocked unconscious or otherwise disabled. The majority of the remainder were killed in action, although it has been estimated that as many as 3,000 continued to resist within the various cave systems for many days afterwards, eventually succumbing to their injuries or surrendering weeks later.

Despite the bloody fighting and severe casualties on both sides, the American victory was assured from the start. Overwhelming American superiority in numbers and arms as well as complete air supremacy—coupled with the impossibility of Japanese retreat or reinforcement, along with sparse food and supplies—permitted no plausible circumstance in which the Americans could have lost the battle.

Joe Rosenthal’s Associated Press photograph of the raising of the U.S. flag on top of the 169 m (554 ft) Mount Suribachi by six U.S. Marines became an iconic image of the battle and the American war effort in the Pacific.

Background
 
Location of Iwo Jima
After the American capture of the Marshall Islands, and the devastating air attacks against the Japanese fortress island of Truk Atoll in the Carolines in January 1944, the Japanese military leaders reevaluated their situation. All indications pointed to an American drive toward the Mariana Islands and the Carolines. To counter such an offensive, the IJA and the Imperial Japanese Navy (IJN) established an inner line of defenses extending generally northward from the Carolines to the Marianas, and thence to Japan via the Volcano Islands, and westward from the Marianas via the Carolines and the Palau Islands to the Philippines.

In March 1944, the Japanese 31st Army, commanded by General Hideyoshi Obata, was activated to garrison this inner line. (Note that a Japanese army was about the size of an American, British Army, or Canadian Army corps. The Japanese Army had many armies, but the U.S. Army only had ten at its peak, with the 4th Army, the 6th Army, the 8th Army, and the 10th Army being in the Pacific Theater. Also, the 10th Army only fought on Okinawa in the spring of 1945.)

The commander of the Japanese garrison on Chichi Jima was placed nominally in command of Army and Navy units in the Volcano Islands. After the American conquest of the Marianas, daily bomber raids from the Marianas hit the mainland as part of Operation Scavenger. Iwo Jima served as an early warning station that radioed reports of incoming bombers back to mainland Japan. This allowed Japanese air defenses to prepare for the arrival of American bombers.

After the U.S. seized bases in the Marshall Islands in the battles of Kwajalein and Eniwetok in February 1944, Japanese Army and Navy reinforcements were sent to Iwo Jima: 500 men from the naval base at Yokosuka and 500 from Chichi Jima reached Iwo Jima during March and April 1944. At the same time, with reinforcements arriving from Chichi Jima and the home islands, the Army garrison on Iwo Jima reached a strength of more than 5,000 men. The loss of the Marianas during the summer of 1944 greatly increased the importance of the Volcano Islands for the Japanese, who were aware that the loss of these islands would facilitate American air raids against the Home Islands, disrupting war manufacturing and severely damaging civilian morale.

Final Japanese plans for the defense of the Volcano Islands were overshadowed by several factors:

• The Imperial Japanese Navy had already lost almost all of its power, and it could not prevent American landings.Aircraft losses in 1944 had been so heavy that, even if war production were not affected by American air attacks, combined Japanese air strength was not expected to increase to 3,000 warplanes until March or April 1945.
• These aircraft could not be used from bases in the Home Islands against Iwo Jima because their range was not more than 900 km (560 mi).
• Available warplanes had to be hoarded to defend Taiwan and the Japanese Home Islands from any attack.
• There was a serious shortage of properly trained and experienced pilots and other aircrew to man the warplanes Japan had because such large numbers of pilots and crewmen had perished fighting over the Solomon Islands and during the Battle of the Philippine Sea in mid-1944.

In a postwar study, Japanese staff officers described the strategy that was used in the defense of Iwo Jima in the following terms:

In the light of the above situation, seeing that it was impossible to conduct our air, sea, and ground/ operations on Iwo Island [Jima] toward ultimate victory, it was decided that to gain time necessary for the preparation of the Homeland defense, our forces should rely solely upon the established defensive equipment in that area, checking the enemy by delaying tactics. Even the suicidal attacks by small groups of our Army and Navy airplanes, the surprise attacks by our submarines, and the actions of parachute units, although effective, could be regarded only as a strategical ruse on our part. It was a most depressing thought that we had no available means left for the exploitation of the strategical opportunities which might from time to time occur in the course of these operations.

— Japanese Monograph No. 48

At the end of the Battle of Leyte in the Philippines, the Allies were left with a two-month lull in their offensive operations before the planned invasion of Okinawa. Iwo Jima was strategically important: it provided an air base for Japanese fighter planes to intercept long-range B-29 Superfortress bombers, and it provided a haven for Japanese naval units in dire need of any support available. In addition, it was used by the Japanese to stage air attacks on the Mariana Islands from November 1944 through January 1945. The capture of Iwo Jima would eliminate these problems and provide a staging area for Operation Downfall – the eventual invasion of the Japanese Home Islands. The distance of B-29 raids could (hypothetically) be cut in half, and a base would be available for P-51 Mustang fighters to escort and protect the bombers.

American intelligence sources were confident that Iwo Jima would fall in one week. In light of the optimistic intelligence reports, the decision was made to invade Iwo Jima and the operation was given the code name Operation Detachment. American forces were unaware that the Japanese were preparing a complex and deep defense, radically departing from their usual strategy of a beach defense. So successful was the Japanese preparation that it was discovered after the battle that the hundreds of tons of Allied bombs and thousands of rounds of heavy naval gunfire had left the Japanese defenders almost undamaged and ready to inflict losses on the U.S. Marines.

Planning and preparation

Japanese preparations
By June 1944, Lieutenant General Tadamichi Kuribayashi was assigned to command the defense of Iwo Jima. Kuribayashi knew that Japan could not win the battle, but he hoped to inflict massive casualties on the American forces, so that the United States and its Australian and British allies would reconsider carrying out the invasion of Japan Home Islands.

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While drawing inspiration from the defense in the Battle of Peleliu, Kuribayashi designed a defense that broke with Japanese military doctrine. Rather than establishing his defenses on the beach to face the landings directly, he created strong, mutually supporting defenses in depth using static and heavy weapons such as heavy machine guns and artillery. Takeichi Nishi’s armored tanks were to be used as camouflaged artillery positions. Because the tunnel linking the mountain to the main forces was never completed, Kuribayashi organized the southern area of the island in and around Mount Suribachi as a semi-independent sector, with his main defensive zone built up in the north. The expected American naval and air bombardment further prompted the creation of an extensive system of tunnels that connected the prepared positions, so that a pillbox that had been cleared could be reoccupied. This network of bunkers and pillboxes favored the defense. For instance, The Nano Bunker (Southern Area Islands Naval Air HQ), which was located east of Airfield Number 2, had enough food, water, and ammunition for the Japanese to hold out for three months. The bunker was 90 feet deep and had tunnels running in various directions. Approximately 500 55-gallon drums filled with water, kerosene, and fuel oil for generators were located inside the complex. Gasoline-powered generators allowed for radios and lighting to be operated underground.

By February 19, 1945, the day the Americans invaded, 18 kilometres (11 mi) of a planned 27 kilometres (17 mi) of tunnel network had been dug. Besides the Nanpo Bunker, there were numerous command centers and barracks that were 75 feet deep. Tunnels allowed for troop movement to go undetected to various defense positions.

Hundreds of hidden artillery and mortar positions along with land mines were placed all over the island. Among the Japanese weapons were 320 mm spigot mortars and a variety of explosive rockets.

Nonetheless, the Japanese supply was inadequate. Troops were supplied 60% of the standard issue of ammunition sufficient for one engagement by one division, and food and forage for four months.

Numerous Japanese snipers and camouflaged machine gun positions were also set up. Kuribayashi specially engineered the defenses so that every part of Iwo Jima was subject to Japanese defensive fire. He also received a handful of kamikaze pilots to use against the enemy fleet. Three hundred and eighteen American sailors were killed by kamikaze attacks during the battle. However, against his wishes, Kuribayashi’s superiors on Honshu ordered him to erect some beach defenses.

American preparations
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, which would become the longest and most intense in the Pacific theater. These would contain a combination of naval artillery shellings and aerial bombings that went on for nine months. On 17 February, 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 February, the Blessman was hit by a bomb from a Japanese aircraft, killing 40 sailors, including 15 members of her UDT.

Unaware of Kuribayashi’s tunnel defense system, many of the Americans assumed the majority of the Japanese garrison were killed by the constant bombing raids.

Pre-landing bombardment
Maj. Gen. Harry Schmidt, commander of the Marine landing force, requested a 10-day heavy shelling of the island immediately preceding the mid-February amphibious assault. However, Rear Adm. William H. P. Blandy, commander of the Amphibious Support Force (Task Force 52), did not believe such a bombardment would allow him time to replenish his ships’ ammunition before the landings; he thus refused Schmidt’s request. Schmidt then asked for nine days of shelling; Blandy again refused and agreed to a three-day bombardment. This decision left much hard feeling among the Marines. After the war, Lieut. Gen. Holland M. “Howlin’ Mad” Smith, commander Expeditionary Troops (Task Force 56, which consisted of Schmidt’s Fifth Amphibious Corps), bitterly complained that the lack of naval gunfire had cost Marine lives during the entire Allied island campaign.

Each heavy warship was given an area on which to fire that, combined with all the ships, covered the entire island. Each warship fired for approximately six hours before stopping for a certain amount of time. Poor weather on D minus 3 led to uncertain results for that day’s bombardment. On D minus 2, the time and care that the Japanese had taken in preparing their artillery positions became clear. When heavy cruiser USS Pensacola got within range of shore batteries, the ship was quickly hit 6 times and suffered 17 crew deaths. Later, 12 small craft attempting to land an underwater demolition team were all struck by Japanese rounds and quickly retired. While aiding these vessels, the destroyer USS Leutze was also hit and suffered 7 crew deaths. On D minus 1, Adm. Blandy’s gunners were once again hampered by rain and clouds. Gen. Schmidt summed up his feelings by saying, “We only got about 13 hours worth of fire support during the 34 hours of available daylight.”

The limited bombardment had questionable impact 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.

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