Mortar fire on Iwo Jima would seriously wound Robert O'Neil. Corporal Eugene Jones took the picture and O'Neil would say he wanted to yell "Put the camera down and pick up a rifle and fight!  I had a mouth full of blood and teeth chips and was trying to get my jaw to spit and up comes this camera."
The Marine Corps logbook indicates the picture was taken on February 20, 1945.  The sequence of pictures was taken from the 19th through the 21st and Jones was with the 4th Division.  
Nick spoke of them running up on Iwo Jima and of O'Neil looking for a place to hit the deck.  The blast went off just above O'Neil snapping him up and over.  When Nick got to his buddy, he was layng with his hands at the sides of his face.  At some point, O'Neil is doing his best to get out "move on, go", but Nick said he wasn't going to leave his buddy there. O'Neil thought he would die on the island and said "I heard him say, the hell you are!"