John C. Robertson was born in Charlestown, Massachusetts, on 31 December 1820. He married Sarah F. Crafts on 9 April 1844 and was employed as a tobacconist and a bookkeeper in Boston prior to the war. In the spring of 1861, Robertson applied for and received a commission as a lieutenant in Company I of the Eleventh Massachusetts. In May of 1862, he was promoted to captain in that same company. He mustered out of service in June 1864 and returned to Charlestown, where he died on 18 June 1865.

The Battle of Bull Run, the first major land battle in the war, was fought in Manassas, Virginia, on Sunday, 21 July 1861. Three Massachusetts regiments -- the First Massachusetts Volunteer Infantry, the Fifth Massachusetts Volunteer Militia, and the Eleventh Massachusetts Volunteer Infantry -- were present on the battlefield. In this letter Robertson captures the essence of the soldier's experience at Bull Run. He begins by indicating that as the Eleventh prepared to leave their camp at Centreville at 2:30 AM they had little information as to what lay ahead, and that the "officers high in command were more ignorant than they should have been" (page 2) about exactly when and where the battle would occur. He states that after marching fifteen miles through the night carrying "two blankets [and] a haversack with three days provisions in it"(page 4) the exhausted men were immediately "formed into column and advanced to the fight" (page 5) where the Eleventh was "constantly engaged and under the hottest fire."(page 7-8)

The letter also describes the human carnage Robertson witnessed (pages 9-11). After revealing that he had been knocked over and had received "a slight wound on the side of my nose," he describes the mortal wound received by John P. Mead, a twenty-seven-year-old private from Lynnfield, Massachusetts. Private Mead had the lower part of his abdomen torn away by a piece of the same shell that had knocked Robertson down and cut his nose. In writing of other men wounded in the battle, Robertson tells his wife he believes "the rebels blew up the Hospital and inhumanly murdered every wounded man." (It was later revealed that many of the wounded were taken prisoner by the Confederates, but the hospitals were not destroyed.) Of the three wounded men Robertson mentions in the letter, Private Mead was the only one killed in the battle. Private Torrey and Captain Gordon were both taken prisoner and later returned to service with the Union Army.

Near the end of the letter, Robertson discusses the breaking up of the Union lines and the retreat in which the men of the many regiments became "so mixed up that it was impossible to collect them together again" (page 14), and reflects on his own feelings about having been in battle (page 15). He closes speaking of the souvenirs -- a bullet and a piece of a bridge -- he attempts to collect at the request of his young son Thomas and expressing his longing to see his wife and children.