Charles L. Brown was born around 1840 in Turner, Maine, to Aaron Brown and Lydia Sawtelle. His father worked as a farmer, and the family moved to Waltham, Massachusetts, sometime before 1850. Aaron died there in February 1853. By 1860, Brown was working as a painter, and the family owned $1,500 of real estate. He enlisted in the Union army on June 29, 1861, and mustered in as a corporal in Company B of the 16th Massachusetts Infantry later that day. He was wounded in action at Charles City Crossroads on June 30, 1862, and sent to Ascension Hospital in Washington, D.C., to recover. He rejoined his regiment by the fall of 1862, and he was promoted to sergeant on November 1, 1862. He was wounded in the Battle of Gettysburg on July 2, 1863, and he died in a hospital several days later.