The Hundred Days Men referred to over eighty regiments of lightly trained militia raised by eight Northern states in 1864 during the Civil War. They were not intended to be front line troops, but to provide rear echelon services such as garrison duty, guarding supplies, transportation and prisoners, and as laborers. This would free up veteran troops that had been doing these necessary tasks so that they could serve in the front lines.

The idea originated with Ohio Governor John Brough. He contacted the governors of five other states, who agreed to raise 100,000 troops. The group then submitted their idea to Secretay of War Edwin M. Stanton. He brought it before President Lincoln, who quickly approved the idea.

The states came up short of their goal, raising about 81,000 men. Ohio provided 36,000 of these. Because of manpower needs, some of the units found themselves involved in the fighting in spite of their intended rear area status.

Regiments of Hundred Days Men

New Jersey

1 regiment was raised which served in the Eastern Theater:

38th New Jersey

Ohio

42 regiments were raised. 33 served in the Eastern Theater:

130th Ohio
131st Ohio
132nd Ohio
133rd Ohio
134th Ohio
135th Ohio
136th Ohio
137th Ohio
138th Ohio
139th Ohio
142nd Ohio
143rd Ohio
144th Ohio
145th Ohio
147th Ohio
148th Ohio
149th Ohio
150th Ohio
151st Ohio
152nd Ohio
153rd Ohio
154th Ohio
155th Ohio
156th Ohio
157th Ohio
159th Ohio
160th Ohio
161st Ohio
163rd Ohio
164th Ohio
166th Ohio
169th Ohio
170th Ohio

New York

8 regiments and 2 artillery batteries were raised. Two served in the Eastern Theater:

28th New York National Guard
56th New York National Guard 

Illinois

13 regiments and 1 battalion were raised. None served in the Eastern Theater.

Indiana

7 regiments were raised. None served in the Eastern Theater.

Iowa

5 regiments were raised. None served in the Eastern Theater.

Kansas

1 regiment was raised, which did not serve in the Eastern Theater.

Wisconsin

3 regiments were raised. None served in the Eastern Theater.