The Hundred Days Men was the nickname applied to a series of regiments of United States Volunteers raised in 1864 for 100-day service in the Union Army during the height of the American Civil War.
These short-term, lightly trained troops freed veteran units from routine duty to allow them to go to the front lines for combat purposes.
Brough proposed to enlist the state militia into federal service for a period of 100 days to provide short-term troops that would serve as guards, laborers, and rear echelon soldiers to free more veteran units for combat duty.
This would increase the number of men in the Northern armies campaigning in the South and allowing the Union to achieve victory more quickly—hopefully in one hundred or fewer days.
Brough expanded the idea and contacted the governors of Indiana, Illinois, Iowa, Wisconsin, and New Jersey to do likewise to raise 100,000 men to offer the Lincoln Administration.