On August 14, 1862, at the age of 44, Towner Brown Jenks enlisted for service with the 37th Massachusetts regiment Company A for three years. They left Pittsfield MA for Washington on September 7, of that year after a ceremony at Park Square in Pittsfield where the community and the Reverend John Todd, with an eloquent prayer, saw them off.

In January 1863, the regiment participated in Burnside's famous "Mud March" near Fredericksburg, after which they returned to their winter encampment near White Oak Church Virginia.

The 37th participated in the capture of Marye's Heights at Frederickburg and on the same day saw action at Salem's Church where in both battles they lost 27 men.

As a part of Eustis' 2nd Brigade, Wheaton's 3rd division, the 37th participated in the forced march of the 6th Corps from Manchester to Gettysburg on the night of the first and morning of the second days of July, 1863 covering 35 miles in 18 hours. On July 3, the day known for Pickett's Charge, the confederate artillary was bombarding the Union line to a degree that much dust was created making the battlefield hard for aiming their guns. As the confederate artillary was firing they were continually adjusting their range to assure at least reaching their target. During this fierce volley, Towner's regiment was returning from reenforcing the 12th Corps on the Northern flank of the Gettysburg engagement. They were marching on Taneytown Road, the low road at the rear of the Union line near Cemetery Hill when some of the confederate shells overshot the Union line and hit the 37th. One shell struck Towner Jenks severing his leg. Towner B. Jenks was discharged for disability January 20, 1864 at Philadelphia.

Sometime after returning home, Towner was employed as Cheshire's telegraph operator with his son Marshall as his message runner where Towner retired in 1883 leaving Marshall to continue.