By Mary Gasper, U. S. Army Military History InstituteJune 4, 2009
In June, 1945, one of the last battles of World War II was finally coming to an end, the Battle of Okinawa. On October 3, 1944, American forces received a directive to seize key positions in the Ryukyu Islands, the island chain that includes Okinawa. Operation ICEBERG, the Okinawa campaignAca,!a,,cs code name, marked the entrance of the United States into the inner circle of Japanese islands in the Pacific. This marked the end of a long journey from Pearl Harbor.
The general scheme for Operation ICEBERG was issued in the fall of 1944 by Admiral Chester Nimitz, the Commander in Chief, Pacific Ocean Areas (CINCPOA). The strategic plan was based on three assumptions. First, the projected campaign against Iwo Jima would have progressed to such an extent that naval fire-support and close air-support units would be in range for the assault on Okinawa. Second, the necessary ground and naval combat units and assault shipping engaged in the Philippines would be released promptly by NimitzAca,!a,,cs counterpart, General Douglas MacArthur, the Commander-in-Chief of the Southwest Pacific Theatre. Third, preliminary air and naval operations against the enemy would ensure control of the air in the target area. The Battle of Okinawa was not going to be easy.
The armament of the Japanese was characterized by a high proportion of artillery, mortar, antiaircraft, and automatic weapons in relation to infantry strength. On Okinawa the Japanese army possessed artillery in greater quantity, size, and variety than had been previously available. . The active formulation of a Japanese defense plan for the Ryukyus dates from the American capture of the Marianas in June and July, 1944. Their first plan for the ground defense of the Ryukyus was established in a 32nd Army directive of July 19, 1944. In the early part of 1945, important changes were made in the original defense plan.
It was decided not to attempt the destruction of the invading forces at the beaches but instead to offer a strong resistance around a central fortified position. On April 5, 1945, the Japanese 383rd Battalion marked the beginning of iron resistance on Okinawa, which led to high casualties and little progress for either side. American attacks on the Japanese lasted only a short time until too many casualties forced the Americans to withdraw. On April 24, on the eastern side of the island the 7th U.S. Division walked up to the top of Hill 178, and they realized that they had finally broken through the first line of Japanese defenses.
By early May, the Americans had successfully broken through the second line of defense and were able to hold this line against the Japanese for longer periods of time. Finally by the end of May, the flower of General Mitsuru UshijimaAca,!a,,cs forces on Okinawa had been destroyed. Three major enemy units had been committed to the line and had all wasted away as a result of naval gunfire, artillery fire, air attacks, and tank and infantry combats. The deaths of General Ushijima and his Chief of Staff, General Isamu Cho, by ritual suicide on June 22 or 23 marked the end of the Okinawa campaign for the 32nd Japanese Army.
The entire campaign lasted eighty-three days. It was not until June 22 that Hill 85 between Medeera and Makabe fell to the 305th U.S. Infantry. The next day the U.S. Tenth Army began a thorough and coordinated mop-up campaign to eliminate the disorganized remnants of the 32nd Japanese Army in southern Okinawa. The plan assigned XXIV Corps and III Amphibious Corps their respective zones of action and fixed three phase lines for the completion of the task.
The mop-up was successfully completed by June 30. Once the American forces turned northward, fewer enemy were found, and the third and final phase line was reached with ease. The final toll of American casualties was the highest experienced in any campaign against the Japanese. Total U. S. Army losses came to 23,000. The U.S. Marine Corps lost another 20,000, and the U.S. and British Commonwealth navies suffered nearly 10,000 more losses. To that staggering total of almost 53,000 must be added another 26,000 non-battle casualties, who were evacuated because of physical and combat fatigue. The high cost of victory was due to the fact that the battle had been fought against a capably led Japanese army of greater strength than anticipated. The campaign had lasted considerably longer than expected, but Americans had demonstrated again on Okinawa that, despite heavy losses, they could win the battle and the campaign. Before summer was over, they would win the war.
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