Around 1910, the nations of South America were in a naval arms race with each participant bent on outdoing a potential enemy. This was the case between Brazil and Argentina when Brazil placed an order for two powerful dreadnought-type vessels with Britain. In response, the Argentine government contracted with the United States for three vessels of similar scope though, due budget constraints, had to curtail their optimistic order to two vessels. Thus the Rivadavia-class was born with the ARA Radavia as the lead ship and her sole sister becoming the ARA Moreno. The ARA Moreno was designed by the Fore River Shipbuilding Company of the United States and constructed by New York Shipbuilding at Camden, New Jersey. Her keel was laid down on July 9th, 1910 and she was officially launched on September 23rd, 1911. The Moreno was then completed in March of 1915 though her formal delivery to the Argentina Navy was delayed until May of that year due to propulsion issues.
The ARA Moreno featured a multi-turreted design with two masts, a pair of funnels and Curtis geared turbines powering three shafts and fed by 18 x Babcock & Wilcox boilers (40,000 shaft horsepower output). Her crew complement included 1,130 sailors and officers required to run her many onboard systems. The vessel displaced at 28,000 under a standard load and 30,600 under a full wartime load, sporting a running length of 270 feet, 3 inches, a beam of 96 feet, 9 inches and a draught of 27 feet, 10 inches. Her inherent range was out to 11,000 nautical miles when making way at 11 knots. Her maximum speed in ideal conditions was approximately 22.5 knots. There were two noticeable superstructures on her profile, the major superstructure forward of amidships (with the bridge) and the lesser superstructure aft. The two masts included the forward lattice mast which towered over the aft pole mast near the second funnel.
As a dreadnought warship, the Moreno gave up armor protection at the expense of speed. The loss of armor was countered by a powerful array of cannon centered around her main battery of 12 x 12" (305mm) guns - these being dual-mounted turrets with two set at the forecastle, two at the stern and two near amidships capable of delivering a fearsome salvo. Some 12 x 6" (152mm) guns were used for shorter-range targets as were 16 x 4" (102mm) guns. She also took on 2 x 21-inch (533mm) torpedo tubes against potential surface threats. Her armor protection included a belt design of up to 12 inches in thickness with 12-inch protection across the turrets and conning tower.
Upon entry into service with the Argentina Navy, the ARA Moreno served with the 1st Division from 1915 to about 1923 before being placed in reserve. In 1924, she was sent to the United States to undergo a major refit that would last until 1925 (the ARA Rivadavia saw a similar modernization during this time). Her propulsion was converted to accept fuel oil (over coal) and her forward mast was shortened. The aft mast was converted from its original pole-style design to a tripod configuration. A new fire control system with rangefinder was installed intended to increase accuracy at range. Her gun batteries were addressed to help improve their base rate-of-fire. The 4" gun batteries were removed and replaced with 4 x 3" (76mm) guns and 4 x 3-pdr cannon for anti-aircraft defense. With the changes in place, engineers even managed to cut some 1,000 tons from the design's displacement and help improve performance and handling to an extent. Upon her return to the Argentine Navy in 1926, the ARA Moreno was utilized as a training ship before rejoining the 1st Division and advancing into the Battleship Division with her sister in due time.
Throughout the 1930s, the ARA Moreno was utilized throughout local South American waters, primarily as a diplomatic messenger. She took part in the 1934 Brazilian Independence celebrations and, in 1937, she and the ARA Rivadavia were sent to Europe on tour. With the officially arrival of World War 2 in 1939, the vessel was recalled to home waters and served locally for the duration of the conflict - Argentina remained neutral throughout the war.
In the post-war years, technology and expense had finally caught up to the decade's old design, forcing the ARA Moreno to be decommissioned in 1949. From then on, she was pressed into service as a barracks/depot ship before being converted to a prison ship during the 1955 Revolucion Libertadora ("Liberating Revolution"). After her official sailing days were over, the ARA Moreno was sold off to Yawata Iron & Steel Company in 1956 to which her hull was transported to Japan (via the Panama Canal) and ultimately scrapped. The ARA Rivadavia suffered a similar fate, being sold to Italy and scrapped in 1957.