Japanese preparations In June 1944, Lieutenant General
Tadamichi Kuribayashi was assigned to command the defense of Iwo Jima. Kuribayashi knew that if the Americans decided to land on Iwo Jima, his garrison 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, might reconsider carrying out an
invasion of the Japanese home islands. Drawing inspiration from Japanese defensive tactics used in the
Battle of Peleliu, Kuribayashi designed a defensive strategy that broke with traditional Japanese military doctrine. Rather than establishing defenses on the beach to contest the landings directly, he opted for
defenses in depth. Kuribayashi's troops constructed a complex system of mutually-supporting fortifications, often linked by a vast tunnel system, equipped with heavy machine guns and artillery.
Takeichi Nishi's armored tanks were camouflaged and used as static artillery positions. Because the tunnel linking
Mount Suribachi to the rest of the island was never completed, Kuribayashi organized the southern area of the island in and around the mountain as a semi-independent sector, with his main defensive zone built up in the north. The expected American naval and air bombardment prompted the creation of an extensive network of tunnels connecting otherwise disparate fighting positions, so that a
pillbox that had been cleared could be later reoccupied. This network of
bunkers and pillboxes was designed for protracted resistance. For instance, the Nanpo Bunker (Southern Area Islands Naval Air HQ) 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 underground with tunnels running in various directions. Approximately five hundred 55-gallon drums filled with water, kerosene, and fuel oil for generators were stored inside the complex. Gasoline-powered generators allowed for radios and lighting to be operated underground. By the time the Americans invaded on 19 February 1945, of a planned of tunnels had been dug. Besides the Nanpo Bunker, there were numerous other command centers and barracks 75 feet below ground. Tunnels allowed for troops to move undetected between defensive positions. Hundreds of hidden artillery and mortar positions were placed all over the island, and many areas extensively mined. Among the Japanese weapons were
320 mm spigot mortars and a variety of explosive rockets. Nonetheless, the Japanese supply situation was inadequate. Troops were supplied 60% of the ammunition normally considered sufficient for single engagement by one division, and food for no more than four months. Numerous Japanese sniper nests and camouflaged machine gun positions were set up. Kuribayashi 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; their attacks during the battle killed 318 American sailors. However, against his wishes, Kuribayashi's superiors on
Honshu ordered him to erect some beach defenses. Starting on 15 June 1944, the
U.S. Navy and the
U.S. Army Air Forces began shore bombardment and air raids against Iwo Jima, which would become the longest and most intense preliminary bombardments in the Pacific Theater. They consisted of a combination of
naval artillery attacks and
aerial bombings, which would last for nine months. Unaware of Kuribayashi's tunnel defense system, some American planners assumed that most of the Japanese garrison had been killed by the constant bombing raids. On 17 February 1945 the
destroyer escort deployed
Underwater Demolition Team 15 (UDT-15) onto Iwo Jima's Blue Beach for reconnaissance. They were spotted by Japanese infantry and fired upon, killing one American diver. On the evening of 18 February,
Blessman was hit with a bomb by Japanese aircraft, killing 40 sailors, including 15 members of the UDT.
Pre-landing bombardment Major General
Harry Schmidt, commander of the Marine landing force, requested a 10-day heavy bombardment of the island immediately preceding his planned
amphibious assault. However, Rear Admiral
William H. P. Blandy, commander of the Amphibious Support Force (Task Force 52), believed that such a bombardment would not 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 insisted upon a three-day bombardment. This decision was resented among the Marines in the landing force. After the war, Lieutenant General
Holland M. "Howlin' Mad" Smith, commander of the Expeditionary Troops (Task Force 56, which consisted of Schmidt's Fifth Amphibious Corps), bitterly complained that a frequent lack of supporting naval gunfire had cost Marine lives throughout the Allied island-hopping campaign. Each heavy warship was assigned an area on Iwo Jima to saturate with shells, ultimately covering the entire island. Each warship fired for approximately six hours before stopping for a certain amount of time. Poor weather on D-3 (three days before the landings) led to uncertain results for that day's bombardment. On D-2, the time and care that the Japanese had taken in preparing their artillery positions became clear. When
heavy cruiser got within range of Japanese shore batteries, the ship was quickly hit six times and suffered 17 dead. Later, 12 small craft attempting to land a UDT were all struck by Japanese fire and quickly retired. While aiding these vessels, the
destroyer was also hit and suffered 7 dead. On D-1, Blandy's gunners were once again hampered by rain and clouds. Schmidt summed up his feelings by stating, "We only got about 13 hours worth of fire support during the 34 hours of available daylight." The limited bombardment had a questionable impact on the enemy since the Japanese were heavily dug-in and well fortified. The craters left behind by the barrage also provided additional cover for the defenders, while hampering the attackers' advance. Despite this, many bunkers and caves were destroyed during the bombardment. The Japanese had been preparing for this battle since March 1944, which gave them a significant advantage. By the time of the landing, about 450 American ships were located off Iwo Jima, and the battle ultimately involved about 60,000 U.S. Marines and several thousand U.S. Navy
Seabees. ==Opposing forces==