A native of New York, and Iowa attorney, William W. Belknap entered the American Civil War in 1861 fighting for the Union. Belknap, having efficiently served at Shiloh and Atlanta, was appointed major general by the end of the war. Belknap was known for serving coolly under pressure at Shiloh and for bravely attacking a Confederate breastwork at Atlanta. At the war's end in 1865, Belknap retired from the military and was appointed internal revenue collector in Keokuk; having served until 1869. After Secretary of War John A. Rawlins died in 1869, President Ulysses S. Grant appointed Belknap to head the War Department. Grant believed Belknap had served with honor and deserved a cabinet position.