During their construction, the two dreadnoughts were subject to numerous rumors involving Argentina selling the two battleships to a country engaged in the First World War, but these proved to be false.

The next decade saw the ship based in Puerto Belgrano as part of the Argentine Navy's First Division before sailing to the United States for an extensive refit in 1924 and 1925.

Moreno's genesis can be traced to the numerous naval arms races between Chile and Argentina, which in turn were spawned by territorial disputes over their mutual borders in Patagonia and Puna de Atacama along with control of the Beagle Channel.

The United Kingdom's Royal Navy bought the two Constitución-class pre-dreadnought battleships that were being built for Chile, and Argentina sold its two Rivadavia-class armored cruisers under construction in Italy to Japan.

[4] These ships, which were designed to carry the heaviest battleship armament in the world at the time,[5] came as an abrupt shock to the navies of South America,[4] and Argentina and Chile quickly canceled the 1902 armament-limiting pact.

The Minister of Foreign Affairs, Manuel Augusto Montes de Oca, remarked that even one Minas Geraes-class ship could destroy the entire Argentine and Chilean fleets.

[1][9] After the two new dreadnoughts were awarded to Fore River, Moreno was subcontracted out to the New York Shipbuilding Corporation of Camden, New Jersey as called for in the final contract.

[11] It was reported in January 1913 that apart from the usual naval requirements for Moreno and her sister ship ARA Rivadavia, two Victrola phonographs apiece were included as part of the official specifications.

[14] Over the course of their construction, Rivadavia and Moreno were the subject of various rumors insinuating that Argentina would accept the ships and then sell them to a European country or Japan, a fast-growing rival to the United States.

Moreno was forced to put in at Rockland, Maine—where many of the observers on board were left to be brought back by train to Camden—before proceeding for repairs to the Fore River Shipyard, which had built the ship's engines.

On the night of 26 March, Moreno accidentally rammed and sank the barge Enterprise in the Delaware River, 30 miles (48 km) south of Philadelphia near the city of New Castle.

The opportunity to show the flag was not missed; Moreno made stops in Valparaiso and Callao before transiting the Panama Canal and sailing north.

[30] Moreno, escorted by the three Mendoza-class destroyers, brought Argentine president Agustín Pedro Justo to Brazil in 1933 for a major diplomatic visit.

When Justo landed and traveled by car to Guanabra Palace, the road was flanked by a plethora of army and naval forces along with thousands of citizens.

[28] Moreno participated in the British Spithead Naval Review, where The New York Times described it as "a strange vestigial sea monster in this company of more modern fighting ships.

The ship was stricken from the navy list on 1 October 1956; on 11 January 1957, Argentina sold Moreno for scrap for $2,468,660 to the Japanese Yawata Iron and Steel Company.