Henry L. Pasco was born around 1840 in Connecticut to Lester and Hannah Pasco. His father was a wholesale grocer and self-described “Gentleman” who owned $4,000 of personal property by 1860. Pasco grew up and attended school in Hartford, Connecticut.
In August 1862, he received a commission as a captain in Company A of the 16th Connecticut Infantry. The regiment took part in the Battle of Antietam, the Battle of Fredericksburg, and the siege of Suffolk. He was promoted to major on June 29, 1863. Confederate forces captured him at Plymouth, North Carolina, on April 20, 1864, and they imprisoned him in Columbia, South Carolina. He escaped in February 1865, and he mustered out on June 24, 1865.
He returned to Hartford after the war, and he earned a living as an insurance adjuster. By 1870, he owned $1,000 of real estate. He died in Hartford on June 3, 1882.