The Marine participated Operation Overstrike and present in Rotterdam. He climbed out of the sewer after James Grayson and Stephen Cartwright defeated a Titan. He was ordered by Cartwright to lead Grayson through the city's sewers. Once in the sewers, the Marine informed Grayson about Boilers. Once they got out of the sewers they found themselves trapped in a empty drainage ditch and unable to proceed. The Marine saw the flood control valve and went over to release the water, but only to be surprised and killed by Leapers. Grayson mourned his death for a moment and quickly moved on to kill the Leapers.
The Marine is also referred to as Private by Stephen Cartwright and rookie by James Grayson, his real name is unknown.