Henry Wager Halleck (1815-1872) was named General-in-Chief of the United States Union forces during the Civil War by President Abraham Lincoln to replace General George Brinton McClellan and was replaced, in turn, by General Ulysses S. Grant.

Many Civil War historians regard Halleck's military successes as unwarranted credit for the strategies of such subordinates as Grant, General John Pope, and General Samuel R. Curtis. He first gained attention as a military strategist of note when he graduated third in his class at West Point Military Academy. He later published a volume of military strategy, Elements of Military Strategy, and served in the Army during the Mexican-American War. President Lincoln recalled him from civilian life to serve as a major general in 1861, and after initial successes, he was named to replace first General John C. Fremont as commander of the Missouri Department and, later, General McClellan as General-in-Chief of...