William Dongisen (and variants) was a recruit who apparently fell ill shortly after enlisting. He was never assigned to a company. Due to his unusual surname and apparent mix-ups in records, the New York Muster Roll Abstract for the 51st Infantry (via Fold3) shows that Pvt William Douzsisen "Never reported to Regiment," whereas the burial register (via Ancestry) shows that William Doncisen of the 58th New York Infantry died at St. Paul's Church Hospital, a Union Army facility. It is virtually certain that these records refer to the same person, a 19-year-old unassigned recruit, born in Germany. The muster roll abstract shows that he enlisted and mustered in at New York City on 17 Aug 1864, just over a month before his death in Alexandria.

The muster roll abstract shows that he previously worked as a mason. He stood 5'2" tall and had blue eyes, light hair, and a light complexion.

An index card at the National Archives (via Fold3) lists an unassigned private named William Donzsisen in the 51st New York Infantry. Possibly additional records at NARA will be found under this spelling.

The burial register and Registers of Deaths of Volunteers (via Ancestry) both show, apparently in error, that he served in the 58th New York Infantry.

This soldier's surname is spelled variously: Dongisen (inscription), Douzsisen (New York muster roll abstract, via Fold3), Donzsisen (National Archives index card, via Fold3, and index for 51st New York Infantry, via Ancestry), Doncisen (burial register), Doucisen (interment control form), Doncison, corrected possibly as Denzioson (Register of Deaths of Volunteers, New York, C-D, image 169, via Ancestry), etc.

Pvt Dongisen's name was not found in a search of the New York adjutant general's muster roll for the 58th New York Infantry (via New York Military Museum website); or in less thorough searches of rosters for the 50th and 51st regiments of New York Infantry.