During the Civil War, he served as a Corporal in the 54th Massachusetts Volunteer Infantry, the first regiment in the United States made up entirely of enlisted men of color. He was 33 years old, single and working as a farmer when he enlisted on 3 March 1863 in Philadelphia, Pennsylvania. Mustered out 25 August 1865 with his regiment.
On 16 April 1863, he was given extra duty as an Acting Corporal.
As new information gets added, double-check these as possible duplicates:
There's a surprising paucity of records with his name so far. There's a Bartender in the 1868 Philadelphia city directory who's a maybe. There's a Welsh American who I'm pretty confident isn't him in Pennsylvania in the federal census.
Year: 1860; Census Place: West Chester, Chester, Pennsylvania; Roll: M653_1094; Page: 641; Family History Library Film: 805094
Jeremiah Davis / b. abt 1828 Delaware / Black / Day Laborer
There are so many 54th soldiers who enlisted in West Chester that this one seems most likely among the candidates so far.
Probably the same person Year: 1870; Census Place: West Chester, Chester, Pennsylvania; Roll: M593_1325; Page: 189A; Family History Library Film: 552824
Year: 1860; Census Place: Philadelphia Ward 23 Precinct 10, Philadelphia, Pennsylvania; Roll: M653_1174; Page: 913; Family History Library Film: 805174
Jeremiah Davis / b. abt. 1825 Pennsylvania / Race unspecified / Shovel Maker
No luck finding a match via Find a Grave or the 1890 US Veterans Schedules yet, even with some pretty creative wild card searched.
He was known to be in New York through military correspondence at some point after the war. No better luck poking around New York records yet.