Here are some places you can investigate further into:
K. Military Records
In addition to showing that a person served in a certain war, military records like muster rolls, payrolls, and discharge lists sometimes give information on age, residence, and occupation. The Historical Society of Delaware library has military records from pre-Revolutionary wars, the American Revolution, the War of 1812, the Civil War, and World War I.
These books, available on the shelves in the reading room, are a good starting point for research in military sources:
Delaware Archives (Fl68/D34)- five volume compilation of documents from pre-Revolutionary wars through War of 1812. Indexes in volumes 3 and 5.
Index to Revolutionary War Pension Applications in the National Archives (E255/P41a)
Revolutionary Pensioners of 1818 (E255/R45)
W.T.R. Saffell, ed., Records of the Revolutionary War (E255/Sl2)
Official Army Register of the Volunteer Force of the United States Army (E548/U58)
Mark Mayo Boatner III, The Civil War Dictionary (E470/B66)
J.Thomas Scharf, History of Delaware, 1607-1888 (Fl66.9/S31) a list of Delaware Civil War soldiers, arranged according to regiment, is in the back of Volume 1.
For additional published works, consult the book catalog under the name of the war or military unit.
Other sources are available in the Historical Society of Delaware Library on microfilm:
Compiled Service Records of Delaware Revolutionary War Soldiers (Microfilm US-5)
Compiled Service Records of Delaware Union Army Volunteers (Microfilm US-6)
Civil War Records from US Provost Marshall General's Bureau and Adjutant General's Office (Microfilm US 3.1)
The Historical Society Library has two special sources on World War I soldiers. One is a series of individual questionnaires filled out by or for returning veterans. They are indexed in the Genealogical Surname File. The questionnaires for individual soldiers may be requested from a librarian. There is also an incomplete listing of Delawareans killed in the war. It is stored in the Manuscript Vault-Cemeteries. Please ask a librarian for this list.
The Historical Society of Delaware manuscript collection contains records from the American Revolution, War of 1812, and the Civil War as well as some militia units and veterans organizations. To find them, look in the manuscript catalog under the name of the war, military unit, commanding officer, or individual soldier.