Before the Battle of Monocacy, B&O agents began reporting Confederate troop movements eleven days prior to the battle, and Garrett had their intelligence passed to authorities in the War Department and to Major General Lew Wallace, who commanded the department responsible for defense of the area. As preparations for the battle progressed, the B&O provided transport for federal troops and munitions, and on two occasions Garrett was contacted directly by President Abraham Lincoln for further information. Though Union forces lost this battle, the delay allowed Ulysses S. Grant to successfully repel the Confederate attack on Washington at the Battle of Fort Stevens two days later. After the battle, Lincoln paid tribute to Garrett as: