In the spring of 1863, Cutler was given command of the 2nd Brigade, James S. Wadsworth's 1st Division, I Corps, which he led at the Battle of Chancellorsville in May, but his unit was only lightly engaged. In the Battle of Gettysburg, they were heavily engaged north of the Chambersburg Pike, (76th New York, 147th New York, and 56th Pennsylvania) withstanding multiple Confederate assaults from the divisions of Maj. Gens. Henry Heth and Robert E. Rodes, coming in from the west and north, respectively. The brigade itself had been split earlier by Maj. Gen. John Reynolds, with a demi-brigade (14th Brooklyn and 95th New York), under the command of Colonel Fowler of the 14th Brooklyn, to engage Brig. Gen. James Archer's brigade south of the Chambersburg Pike. By the time the I Corps line broke around 4 p.m., his brigade had suffered over 50% casualties.