Despite the fact that the outcome was never in question and that the fighting was only the result of Japanese military commanders who wanted to frighten the Americans with the prospect of sustaining huge casualties if the US decided to invade Japan.
The Japan's military commanders were completely successful. Their brainwashing meant that 98% of the Japanese soldiers involved were either killed by enemy action or committed ritual suicdie. Only 216 Japanese soldiers were captured, almost all of them were too critically wounded to carry out their own suicide.
The result was that while virtually the entire Japanese force was killed the Americans still sustained more casualties than the Japanese with 6,822 dead 19,217 wounded.
It was this result at Iwo Jima that led American civilian and military leaders to conclude that a gradual invasion of Japan would cause millions of casualties on both sides and that the use of an atomic weapon could provide the dramatic ending to a war that would save allied and Japanese lives.
The fact that the same results were experienced on Okinawa where the Japanese military convinced civilians to engage in mass suicide confirmed the impression made at Iwo Jima
With the impending victory of American troops, civilians often committed mass suicide, urged on by the Japanese soldiers who told locals that victorious American soldiers would go on a rampage of killing and raping. Ryukyu Shimpo, one of the two major Okinawan newspapers, wrote in 2007: "There are many Okinawans who have testified that the Japanese Army directed them to commit suicide. There are also people who have testified that they were handed grenades by Japanese soldiers (to blow themselves up)."<31> Some of the civilians, having been induced by Japanese propaganda to believe that U.S. soldiers were barbarians who committed horrible atrocities, killed their families and themselves to avoid capture. Some of them threw themselves and their family members from the cliffs where the Peace Museum now resides.
http://en.wikipedia.org/wiki/Battle_of_Okinawa#Rape_allegations.2C_mass_suicide