On May 14, he was killed after running through intense hostile fire to reach an abandoned machine gun during a mission to evacuate wounded soldiers.
Private First Class Diamond's official Medal of Honor citation reads: As a member of the machinegun section, he displayed extreme gallantry and intrepidity above and beyond the call of duty .
When 2 infantry companies established a bridgehead, he voluntarily assisted in evacuating the wounded under heavy fire; and then, securing an abandoned vehicle, transported casualties to the rear through mortar and artillery fire so intense as to render the vehicle inoperative and despite the fact he was suffering from a painful wound.
On 14 May 1945, when leading a patrol to evacuate casualties from his battalion, which was cut off, he ran through a virtual hail of Japanese fire to secure an abandoned machine gun.
Diamond's indomitable spirit, constant disregard of danger, and eagerness to assist his comrades, will ever remain a symbol of selflessness and heroic sacrifice to those for whom he gave his life.