Gilbert Wesley Marsh Cordes was born May 5, 1928 in Braintree, Norfolk County, Massachusetts. His parents were William J Cordes and Marian Cordes. The family moved from Massachusetts to Georgia between 1930 and 1940.

Marsh Cordes attended the Druid Hills High School, Emory University and the Georgia Military Academy. He enlisted in the Marine Corps and served in the 5th Marine, First Marine Division.

Second Lieutenant Gilbert Marsh Cordes was killed in Korea on April 9, 1952. The cause of casualty is listed as hostile gunshot or small arms fire, and place of death is listed as Hwanghaebuk-to, North Korea.

According to the Atlanta Constitution (June 26, 1959), "In the middle year of the Korean war [Marsh Cordes] was leading a patrol on a night raid against the enemy far in advance of his own lines. Suddenly his patrol found itself under heavy enemy mortal, machine gun and small arms fire. The enemy was fighting from a well-entrenched position. Marsh left his men forward in a daring assault on the hostile position. In the intensive fighting he was killed.

Cordes' funeral was held at the graveside in Decatur Cemetery.

One of Marsh's brothers, William J. Cordes, Jr. was killed in action in 1945 in Germany.

His father, William J. Cordes, Sr., who served in World War I, corresponded with various people about his son's death.