The "21 Guns" WOD is a functional fitness tribute workout designed for the "WOD With Warriors" event, which takes place twice a year on Veterans Day and Memorial Day in the United States. The purpose of this workout is to honor and pay tribute to the nation's warriors, past, present, and future.

The workout's structure and repetitions symbolize a 21-gun salute, a traditional military honor rendered at funerals and memorial services. Each exercise represents one of the five branches of the military. The 21-minute duration of the workout is also significant, as it represents the 21-gun salute, the highest display of honor in the United States, reserved for fallen troops on Memorial Day.

Lt. Murphy was the leader of a four-man SEAL reconnaissance unit that secretly infiltrated into the Hindu-Kush mountains on June 27, 2005. Ambushed on the 28th by overwhelming Taliban forces, Murphy valiantly climbed into the open onto high ground to make an electronic call for rescue. Wounded, he fought on, allowing one member of his squad to escape, before he himself was killed. Lt. Michael Murhpy was awarded the Medal of Honor on October 27, 2007. He is only the third service member to earn that highest national honor since President Bush sent U.S. military forces to Afghanistan in 2001, and later to Iraq. He is also the first Navy recipient since the Vietnam War.