At the beginning of the Civil War, the younger Gilder enlisted in the 5th New York Infantry (Duryée's Zouaves), was transferred to the 40th New York, and was mustered out with the rank of captain and brevet major.
The passage describes the military career of the younger Gilder during the Civil War. He initially joined the 5th New York Infantry (Duryée's Zouaves), was transferred to the 40th New York, and ultimately received his discharge as a captain with the rank of brevet major.