As governor, Brough strongly supported the Lincoln Administration's war efforts and was key to persuading other Midwestern governors to raise 100-day regiments in early 1864 to release more seasoned troops for duty in Gen. Ulysses S. Grant's spring campaign. Ohio contributed more than 34,000 troops, and was the only one of the five participating states (the others were Indiana, Illinois, Iowa and Wisconsin) to exceed its quota. Brough supported Lincoln's reelection in 1864, despite the machinations of Ohio's favorite son Salmon P. Chase, and worked tirelessly to support the state's soldiers in the field. When Chase resigned as Secretary of the Treasury, Brough was offered the position but declined it to remain as governor.