Editing Battle of Iwo Jima (section)

==Background==
[[File:Iwo jima location mapSagredo.png|thumb|left|Location of Iwo Jima]]
After the [[Gilbert and Marshall Islands campaign|American capture of the Marshall Islands]] and the [[Operation Hailstone|air attacks]] against the Japanese fortress island of [[Chuuk Lagoon|Truk Atoll]] in the [[Caroline Islands|Carolines]] in January 1944, Japanese military leaders reevaluated their strategic position. 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, from there 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 [[Thirty-First Army (Japan)|Japanese 31st Army]], commanded by General [[Hideyoshi Obata]], was activated to garrison this inner line. (Note that an army-sized unit in Imperial Japanese military doctrine was about the size of an American, [[British Army]], or [[Canadian Army]] [[corps]]. The Japanese Army had many [[Armies of the Imperial Japanese Army#Armies|armies]], but the [[U.S. Army]] had only [[formations of the United States Army during World War II#Field Armies|ten]] at its peak, with the 4th Army, the 6th Army, the 8th Army, and the 10th Army being in the [[Pacific War|Pacific Theater]]. The 10th Army only saw action at the end of the Pacific war, landing on [[Battle of Okinawa|Okinawa]] in the spring of 1945.)

The commander of the Japanese garrison on [[Chichi Jima]] was placed nominally in command of IJA and IJN units in the Volcano Islands.{{sfn|Morison|1960|p=14}} After the American conquest of the Marianas, daily bomber raids from the Marianas began to hit mainland Japan as part of [[Operation Scavenger]]. Iwo Jima served as an early warning station that radioed reports of incoming bombers back to the Home Islands, allowing Japanese air defenses to prepare for the arrival of American bombers.{{sfn|Morison|1960|p=46}}

After the U.S. seized bases in the Marshall Islands in the battles of [[Battle of Kwajalein|Kwajalein]] and [[Battle of Eniwetok|Eniwetok]] in February 1944, Japanese 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 [[Japanese archipelago|Japanese home islands]], the army garrison on Iwo Jima reached a strength of more than 5,000 men.{{sfn|Morison|1960|p=14}} The loss of the Marianas during the summer of 1944 greatly increased the importance of the Volcano Islands for the Japanese, who were concerned that the loss of those islands would further facilitate American air raids against the Home Islands, disrupt war manufacturing, and severely damage civilian morale.{{sfn|Morison|1960|p=67}}

The final Japanese plans for the defense of the Volcano Islands were hamstrung by several factors:

# The Combined Fleet had lost almost all of its striking power during naval engagements in the latter half of 1944, and could not interdict American landings.
# Aircraft losses in 1944 had been so severe that even if war production was not affected by American air attacks, the combined Japanese air strength was not expected to increase to 3,000 warplanes until March or April 1945.
# Those aircraft could not be used from bases in the home islands to support the defense of Iwo Jima because their range was not more than {{cvt|900|km|mi}}.
# Available warplanes had to be hoarded to defend [[Taiwan under Japanese rule|Taiwan]] and the home islands from any attack.{{sfn|Morison|1960|p=50}}
# There was a serious shortage of properly trained and experienced Japanese pilots because such large numbers of pilots and crewmen had perished fighting over the [[Solomon Islands]] in 1942 and during the [[Battle of the Philippine Sea]] in mid-1944.

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

{{blockquote|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 [[kamikaze|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.<ref>{{harvnb|Japanese Monograph No. 48|p=62}}, cited in {{harvnb|Garand|Strobridge|1971|p=450}}.</ref>||Japanese Monograph No. 48}}

After the [[Battle of Leyte]] in the Philippines, the [[Allies of World War II|Allies]] were left with a two-month lull in their offensive operations before the planned [[Battle of Okinawa|invasion of Okinawa]]. Iwo Jima was considered strategically important since it provided an air base for Japanese [[fighter aircraft|fighter planes]] to intercept long-range [[Boeing B-29 Superfortress|B-29 Superfortress]] bombers flying to strike targets in Japan. In addition, it was used by the Japanese to stage intermittent [[Japanese air attacks on the Mariana Islands|air attacks on the Mariana Islands]] from November 1944 to January 1945. The capture of Iwo Jima would eliminate those problems. The island's airfield would also support [[North American P-51 Mustang|P-51 Mustang]] fighters, which could escort and protect bombers en route to Japan.{{sfn|Morison|1960|p=120}}

American intelligence sources were confident that Iwo Jima would fall in one week. In light of optimistic intelligence reports, the decision was made to invade Iwo Jima, and the operation was codenamed Operation Detachment.{{sfn|Morison|1960|p=100}}