Editing Battle of Iwo Jima (section)

===Japanese preparations===
[[File:Tadamichi Kuribayashi.jpg|upright|thumb|Lieutenant General Tadamichi Kuribayashi]]
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 [[Operation Downfall|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 his defenses on the beach to contest the landings directly, he instead opted for [[Defence in depth|defenses in depth]]. Kuribayashi's troops constructed a complex system of mutually-supporting fortifications, often linked together by a vast tunnel system, equipped with heavy machine guns and artillery. [[Takeichi Nishi]]'s armored tanks were camouflaged and utilized 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 (military)|pillbox]] that had been cleared could be reoccupied later. This network of [[bunker]]s and pillboxes strongly favored the defense, and was designed for protracted resistance. For instance, the Nanpo Bunker (Southern Area Islands Naval Air HQ), which was 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, and had 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.{{sfn|King|2014|pp=58–59}}

By the time the Americans invaded on 19 February 1945, {{cvt|18|km|mi}} of a planned {{cvt|27|km|mi}} of tunnels had been dug. Besides the Nanpo Bunker, there were numerous other command centers and barracks that were 75 feet below ground. Tunnels allowed for troops to move undetected between various defensive positions.{{sfn|Hammel|2006|p=36}} Hundreds of hidden artillery and mortar positions were placed all over the island, and many areas were extensively mined. Among the Japanese weapons were [[320 mm Type 98 mortar|320 mm spigot mortars]] and a variety of explosive rockets.{{sfn|King|2014|p=80}} 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.{{sfn|Japanese Monograph No. 45|p=257}}

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;{{citation needed|date=January 2021}} 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.{{citation needed|date=January 2021}}

Starting on 15 June 1944, the [[United States Navy|U.S. Navy]] and the [[United States Army Air Forces|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.<ref>{{cite web |title=Chronology of the Battle of Iwo Jima |url=http://www.nps.gov/archive/wapa/indepth/pactheatercamp/iwo/chronology.htm |url-status=dead |archive-url=https://web.archive.org/web/20100707082542/http://www.nps.gov/archive/wapa/indepth/pactheatercamp/iwo/chronology.htm |archive-date=7 July 2010}}</ref> They consisted of a combination of [[naval artillery]] attacks and [[strategic bombing|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]] {{USS|Blessman|DE-69|6}} 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.