FTP name this Union soldier.
His Elements of Military Art and Science, a course of lectures delivered at West Point, was published in book form in 1846, and later became the standard textbook for volunteer officers in the Civil War.  As supreme commander of the Western theater in 1861, he displayed considerable administrative ability in forming effective fighting units from the masses of volunteers, and earned a promotion to general-in-chief of the Union forces in 1862.  Often at odds with his subordinate generals and unable to develop an effective offensive strategy, he was replaced by Grant in 1864.  FTP name this Union soldier.
His Elements of Military Art and Science, a course of lectures delivered at West Point, was published in book form in 1846, and later became the standard textbook for volunteer officers in the Civil War.  
Henry Halleck