New Hampshire was particularly active in the Caribbean during this period, as several countries, including Haiti, the Dominican Republic, and Mexico devolved into internal political conflicts.

After the United States entered World War I in April 1917, the ship was used primarily to train gunners and engine room personnel, as the US Navy had expanded significantly to combat the German U-boat campaign.

New Hampshire remained in service for only a few years after the war, as the 1922 Washington Naval Treaty significantly reduced the navies of the signatories; as a result, the ship was sold for scrap in November 1923.

The Connecticut class followed the Virginia-class battleships, but corrected some of the most significant deficiencies in the earlier design, most notably the superposed arrangement of the main and some of the secondary guns.

Despite the improvements, the ships were rendered obsolescent by the revolutionary British battleship HMS Dreadnought, completed before most of the members of the Connecticut class.

As was standard for capital ships of the period, New Hampshire carried four 21 inch (533 mm) torpedo tubes, submerged in her hull on the broadside.

After completing final fitting-out work, New Hampshire transported a Marine Expeditionary Regiment to Colón, Panama on 20 June, arriving six days later.

She then made a series of visits to ports on the eastern coast of North America, including Portsmouth, New York, and Bridgeport, along with a stop in the Canadian province of Quebec.

On 22 February 1909, she participated in a Naval Review for President Theodore Roosevelt to greet the return of the Great White Fleet in Hampton Roads, Virginia.

[3] During this period, Ernest King, later the Chief of Naval Operations during World War II, served aboard the ship in the engine room.

[3] On 21–22 March, New Hampshire conducted gunnery training with the target ship San Marcos—the old battleship Texas—in Tangier Sound in Chesapeake Bay.

This time the ships cruised into the Baltic Sea, stopping in several ports in Germany, Russia, and Scandinavia, before returning to New England on 13 July.

On 2 December, she steamed to Santo Domingo, the capital of the Dominican Republic, where the United States had instituted a military government under Rear Admiral Harry Knapp in an attempt to put an end to the political instability there.

Over the course of the next eighteen months, the ship was occupied with training gunners and engine room personnel for the rapidly expanding wartime fleet.

While the ships stopped to regain control of the situation, a lookout reported a periscope from a U-boat; New Hampshire and the battleship USS Ohio opened fire with their 6-inch guns to no effect.

On 25 January she crossed the Atlantic to Europe for the final time to carry the remains of August Ekengren, the Swedish envoy to the United States.