Warren French, a Boston carpenter and stair builder, was born at New Sharon, Maine, ca. 1822. He joined the Ancient and Honorable Artillery Company of Massachusetts on April 25, 1851 and was honorably discharged from the company on May 11, 1857.

French joined the 11th Massachusetts Independent Battery as a captain in August 1862 during the American Civil War. In November, the unit was assigned to defend Washington, and it remained in northern Virginia until returning to Boston, where it mustered out on May 11, 1863. French joined Company A of the 42nd Massachusetts Volunteer Militia (100 days men) as its captain on July 14, 1864. Following his Civil War service, he rejoined the Artillery Company on May 15, 1865 and was again honorably discharged on May 13, 1867. Warren French died on May 19, 1879.

The 42nd Massachusetts Volunteer Militia was organized at Reedville, Massachusetts. Company A seems to have been organized around a unit known as the Franklin Light Battery of Boston. The regiment was mustered into United States service in July 1864, and was assigned to guard duty at Washington D.C. where it was largely responsible for maintaining security of the trains transporting supplies between Washington and the Shenandoah Valley. The regiment was mustered out of service on November 11, 1864.