In November 1901, MacArthur was aboard the Fulton when it set an underwater endurance record of 15 hours on the bottom of Peconic Bay, New York.
[4][5][6] Later, MacArthur was injured when, on a run from New Suffolk, New York, to Washington, D.C., to exhibit the submarine to naval committees of the House and Senate, the Fulton experienced a battery explosion off the Delaware Breakwater.
At the Naval Academy, he served initially as aide to the superintendent, Admiral James H. Sands[12][13] and subsequently on the staff for the commandant of midshipmen.
MacArthur was a hereditary member of the Military Order of the Loyal Legion of the United States by right of his father's having served as a Union officer in the Civil War.
Chattanooga engaged in the important, exacting and hazardous duty of transporting and escorting troops and supplies to European ports through waters infested with enemy submarines and mines."