A reference here from the son regarding corporal John C. Corbett who threw the rock.
http://www.historynet.com/battle-of-okinawa-the-bloodiest-battle-of-the-pacific-war.htm
10/15/2011
My dad was corporal John C. Corbett first marine to reach the lower end of Okinawa.Read The Complete History of World War II by Francis Trevelyan Miller page933 1st prg. Eighth Regimental combat team Second Marine Division. Anyone out there who served in thjs unit?
Wow. A lot of history in those comments. The son of the medic who pronounced General Buckner dead also commented. As well as someone who was stationed there 20 years later and found places where you could not see the ground through the shrapnel. And the Japanese gentleman trying to learn of his uncle’s fate.