It was April 4th, 2004, and troops from the 1st Cavalry, out of Fort Hood, Texas had just arrived in Iraq. They had been handed a routine mission, escorting Iraqi sewage trucks through a Baghdad suburb, and they were done for the day, headed back to base. Then the streets emptied, machine gun fire and rocket-propelled grenades rained down. Eight Americans died in the ambush that day, and 65 were wounded. For the U.S. military, it marked what was, at the time, the worst single day in terms of casualties since Vietnam.