Neither side expected it to be the last major battle of the war, which it was. The Americans were planning Operation Downfall, the invasion of the main islands of Japan, which never happened, due to the Japanese surrender resulting from the American use of the atomic bomb in August 1945, first in Hiroshima, and a second time in Nagasaki.  The battle has been referred to as "Typhoon of Steel" in English, and "tetsu no ame," "tetsu no bōfū" by Okinawans, which means "rain of steel" and "violent wind of steel" respectively, referring to the intensity of gunfire that characterized this battle.  At some battles such as Iwo Jima, there had been no civilians, but Okinawa had a large indigenous civilian population, and the civilian losses in the battle were at least 130,000. American losses were over 72,000 casualties, of whom 18,900 were killed or missing, over twice the number killed at Iwo Jima, and the Guadalcanal combined. About a quarter of the civilian, Japanese, and American populations about, around or upon the island in spring of 1945 were killed. There were about 107,000 Japanese soldiers or civilians killed or captured. Some of the soldiers committed seppuku or simply blew themselves up with grenades. Some of the civilians, having been convinced by Japanese propaganda that the Americans were "barbarians" who committed horrible atrocities, killed their families, and then themselves, rather than being captured.  Rear Admiral Minoru Ota commanded the Naval Base Force that defended the Oroku Peninsula on Okinawa. On 11 June 1945, the U.S. 6th Marine Division encircled the Naval Base Force and Ota sent his farewell telegram to the 32nd Army Headquarters at 1600, 12 June. On 13 June, Ota committed suicide.