[1] In June 1877, Wood applied to take the competitive examination for admission to the United States Military Academy at West Point, New York, but was turned away for being too young.

In 1878, he was appointed to the United States Naval Academy at Annapolis, Maryland, from the 1st Congressional District of New York by Congressman James W. Covert.

After about a year, he transferred in 1883 to duty as an aide on the staff of Rear Admiral George H. Cooper, commander of the Home Squadron, aboard the screw frigate USS Tennessee, during which duty he accompanied Cooper on a visit to Caracas, Venezuela, to attend the unveiling of a statue of George Washington there.

In November 1888 he was among a group of four officers ordered to Mexico and Central America to make astronomical observations to determine the longitude of Coatzacoalcos and Salina Cruz in Mexico, La Libertad in El Salvador, and San Juan del Sur in Nicaragua; the group then traveled to Washington, D.C., to complete its calculations.

In March 1893 he became naval aide to United States Secretary of the Navy Hilary Abner Herbert, and during his tour, which lasted over a year, oversaw many of the details related to guests invited to the 1893 Naval Review in New York City, accompanied Herbert to New York aboard the gunboat and dispatch vessel USS Dolphin, and escorted President Grover Cleveland from Jersey City, New Jersey, to his hotel and the following day from his hotel to Dolphin for the review.

[1] At his own request, Wood was relieved of his duties in the spring of 1894 so that he could become flag secretary to Rear Admiral John G. Walker, who was taking command of the Pacific Squadron at the time with orders from President Cleveland to observe and report on developments in the Hawaiian Islands, governed by a provisional government in the aftermath of the 1893 overthrow of the Kingdom of Hawaii.

Promoted to lieutenant, junior grade, on 11 April 1894 and serving aboard the protected cruiser USS Philadelphia at Honolulu while in the Pacific Squadron, Wood in his duties supporting Walker observed Hawaii's Constitutional Convention and was present at the 4 July 1894 proclamation of that constitution as law, establishing the Republic of Hawaii.

[1][2] Wood next became flag secretary to Rear Admiral Richard W. Meade, the commander of the North Atlantic Squadron, aboard the armored cruiser USS New York.

[1] After turning Du Pont over to the Naval Torpedo Station at Newport in the autumn of 1898, Wood reported for duty aboard the battleship USS Massachusetts.

On 24 December 1917, Secretary of the Navy Josephus Daniels announced the promotion of twelve captains to a temporary rank of rear admiral for World War I service, and Wood was among them.

He remained aboard Oklahoma until 1 February 1918, involved primarily in the training of her crew and a refit of the ship, and received the Navy Cross for "exceptionally meritorious service" while in command of her.

[1] Margaretta Wood was a longtime confidante of the American naval spy Commander Hugo W. Koehler (1886–1941), step father of United States Senator Claiborne Pell (D-RI).