Battery D was engaged at the first battle of Bull Run on 21 July 1861 (this battery was organized on 7 January 1861 at the U.S. Military Academy at West Point, and was known as the "West Point Battery"). Future major general Adelbert Ames was a 1st lieutenant in the battery during the battle and remained on the field to direct fire though severely wounded; he later received the Medal of Honor for this action. Colonel Harvey Brown, the regiment's first commander, led an expedition that reinforced and defended Fort Pickens, Florida in 1861. He was apparently detached from the regiment, as none of its batteries were on the expedition. He retired on 1 August 1863. Thomas W. Sherman was briefly the regiment's lieutenant colonel in 1861, during training at Camp Greble. In April 1862 the regimental headquarters moved to Fort Hamilton in Brooklyn, New York. The regiment's batteries were organized gradually from July 1861 through November 1862, with Battery D in existence from 7 January 1861. Seven batteries of the regiment were organized by the end of September 1861.