Marshall was 50, the oldest soldier in his brigade, when he took the lead on a scout convoy protecting a vital fuel and ammunition convoy headed for Baghdad on April 7, 2003, during the U.S.-led invasion of Iraq.
Marshall was killed by a rocket-propelled grenade that blew his body out of the Humvee. Polsgrove, then 26, faced an agonizing decision: try to recover Marshall's body and expose his troops to intense enemy fire, or get out of the kill zone and come back for him later.
Polsgrove decided to save the living, a decision that haunted him. He had idolized Marshall. The sergeant was a source of wisdom and strength for the men, who for the most part were half his age. If Marshall had not taken the lead, Polsgrove believed he would have been in the first vehicle.
In large part because of Marshall's scout team, the convoy arrived safely in downtown Baghdad. It gave Marshall's brigade, the 2nd Brigade of the 3rd Infantry Division, the fuel and ammunition it needed to seize the capital, after which Saddam Hussein's regime toppled.
Marshall's death devastated the unit. The brigade had lost just six men in the previous three weeks. Marshall was the 145th U.S. service member to die in Iraq at a time when most soldiers believed the war was almost over.
Polsgrove and other soldiers were determined to recover Marshall's body. For days, they searched the highway where he died. Finally, five days after Marshall's death, an Iraqi boy led U.S. soldiers to a shallow grave that contained his remains.
His body was returned to his wife and six children. Marshall was awarded a Bronze Star and Purple Heart and buried with full military honors at Arlington National Cemetery.
Polsgrove believes Marshall's actions saved his life. The following year, Polsgrove's wife gave birth to the couple's first child, which he considers to be a miracle that would not have happened without the sacrifice of John W. Marshall.