This is great Mr. Martin! Thank you so much for your information, very helpful! I recently discovered that Daniel Stephens McCarthy had a brother, Samuel H McCarthy, who also fought in the war, although not in the Howitzers. He was in Otey's Light Artillery Battery which was also organized in Richmond. Are your resources able to find any information concerning him?

Below is an article concerning his death.
Died. At the residence of James T. Butler, in Caroline county, VA., on Sunday the 16th instant, of consumption, Samuel H. McCarthy, in the twenty-second year of his age. The deceased was a son of the late Daniel S. McCarthy, of this city, and during the war a member of the “Otey Battery;’ and received in an engagement a severe wound in the year 1864 which shattered and undermined his constitution, and producing eventually a lingering and wasting disease. Richmond Dispatch - Sep 18 1866