John Mallon, 37th., New York, Infantry.

New York State Records.

New York 37th., Infantry.

MALLEN, "MALLON" JOHN.—Age, 31 years. Enlisted, May 16, 1861, at New York city, to serve two years; mustered in as private, Co. G, June 7,1861; died, January 29, 1862, of wounds received at Occoquan, Va.

Authors note.  I believe they were talking about Occoquan river, which is in Fairfax county Virginia.
In the next piece of information you will see he was wounded in a town and taken to another town and both towns are near the Occoquan river.

American Medical Times, 1862.

John Mallon, private, Company G., 37th., New York Volunteers, was wounded in a midnight attack on the enemy at Colchester, Virginia, on January 27, 1862.  Though considerably shocked, he was still able to assist his comrades to batter in the door of the house occupied by the enemy, when he sank exhausted.  He was conveyed on horseback seven miles to the village of Acotink, Virginia, where he was attended to, died sixteen days later.