Bay Stater Ezra Cowles was born in 1843, and when recruitment for a new Massachusetts regiment of infantry was being raised near Pittsfield, he enlisted in Company D, 37th Massachusetts Infantry on September 2nd, 1862. Erza was promoted to the rank of Corporal on  March 1st, 1863, and then once more to 1st Sergeant of his company on September 20th, 1864. He was present with the 37th Massachusetts for its entire service leading up to the Appomattox Campaign, except for a number of months from July 1863 - June 1864 when Ezra was detailed to go back to Massachusetts to recruit men and gather up conscripts.

During the Appomattox Campaign, the 37th Massachusetts was heavily engaged near the Hillsman Farm at the Battle of Sailor’s Creek on April 6th, 1865. Ezra and his fellow Bay Staters were armed with Spencer Repeating Rifles, giving them an advantage as they crossed Little Sailor’s Creek and engaged Richard Ewell’s dug in Confederates. Ezra was mentioned in the 37th Massachusetts’ regimental history:

"The 37th Regiment marched from Petersburg, Va. more than 20 miles over the sandy, rolling, pine-covered country on April 6, 1865 before [its soldiers] 'began to fill the magazines of their rifles, to cast aside knapsacks, blankets and superfluous clothing in preparation for the anticipated struggle.' The men were ready to break into a run when the order to "double-quick" was received, and for three miles they went forward at [that] pace ... Once across [Sailor's/Saylor's/Sayler's] creek the lines were deployed, the Thirty-seventh on the left of the brigade with a detail of skirmishers covering the front, and an advance was ordered up the hill and through the thicket toward the position of the unseen enemy…. As the foot of the ascent was reached the lines were again adjusted, moved by the right flank for a short distance, and once more advanced up the slope. A scattering fire was immediately encountered from the enemy's skirmishers, and one of the first of the Thirty-seventh to fall was First Sergeant Ezra P. Cowles of Company D, which he commanded, Captain Edwards acting as major. Sergeant Cowles was mortally wounded through the body, but heroically cheered on his comrades as he fell."

Following the vicious fighting, Ezra was carried to the field hospital at the Hillsman farm, where he began to receive medical attention. Shortly thereafter, he was transported to Burksville, Virginia. Unfortunately, while at Burksville, Ezra succumbed to his wounds on April 9th, 1865, the same day General Robert E. Lee surrendered his Confederate Army of Northern Virginia at Appomattox Court House.