H. W. (Henry Wager) Halleck

Henry Wager Halleck was a senior United States Army officer, scholar, and lawyer. A noted expert in military studies, he was known by a nickname that became derogatory: "Old Brains". He was an important participant in the admission of California as a state and became a successful lawyer and land developer. Halleck served as the General-in-Chief of the Armies of the United States from 1862 to 1864, and then became Chief of Staff for the remainder of the war when Ulysses S. Grant was appointed to that position.