Career
Born in 1844 at Philadelphia, Pennsylvania, Sapp later joined the Navy from that state. By December 15, 1871, he was serving as a seaman in the engineering department of the United States Ship Shenandoah. On that day, while the Shenandoah was at Villefranche-sur-Mer, France, he jumped overboard and, with Midshipman Miller, rescued Seaman Charles Prince from drowning.
His first name was misspelled as "Isacc" on the citation.
On board the United States.S. Shenandoah during the rescue of a shipmate at Villefranche, 15 December 1871. Jumping overboard, Sapp gallantly assisted in saving Charles Prince, seaman, from drowning.