The First World War effectively ended the dreadnought race, as all three countries suddenly found themselves unable to acquire additional warships. After the conflict, the race never resumed, but many plans for post-war naval expansions and improvements were postulated by the Argentine, Brazilian, and Chilean governments. The Brazilians modernized
Minas Geraes,
São Paulo, and the two cruisers acquired under the 1904 plan, and , between 1918 and 1926. This was sorely needed, as all four ships were not ready to fight a modern war. Although the Brazilian government intended to send
São Paulo overseas for service in the
Grand Fleet, both it and
Minas Geraes had not been modernized since entering service, meaning they were without essential equipment like modern
fire control. Maintenance on the two ships had also been neglected, which was most clearly illustrated when
São Paulo was sent to New York for modernization: fourteen of its eighteen boilers broke down, and the ship required the assistance of the American battleship and cruiser to continue the voyage. The two cruisers were in poor condition and were only able to steam at a top speed of thanks to a desperate need for new
condensers and boiler tubes. With repairs, both participated in the war as part of
Brazil's main naval contribution to the conflict. The Brazilian Navy also made plans to acquire additional ships in the 1920s and 30s, but both were sharply reduced from the original proposals. In 1924, they contemplated constructing a relatively modest number of warships, including a heavy cruiser, five destroyers, and five submarines. In the same year, the newly arrived American naval mission, led by Rear Admiral
Carl Theodore Vogelgesang, tendered a naval expansion plan of , divided between battleships (70,000), cruisers (60,000), destroyers (15,000), and submarines (6,000). The United States' State Department, led by Secretary of State
Charles Evans Hughes and fresh from negotiating the
Washington Naval Treaty, was not keen on seeing another dreadnought race, so Hughes quickly moved to thwart the efforts of the mission. Only one Italian-built submarine, , was acquired during this time. By the 1930s, the international community believed that the bulk of the Brazilian Navy was "obsolete" and were old enough to no longer be "considered effective". Still,
Minas Geraes was modernized a second time at the
Rio de Janeiro Navy Arsenal from June 1931 to April 1938. Plans to give similar treatment to
São Paulo were dropped due to the ship's poor material condition. During the same period, the Brazilian government looked into purchasing cruisers from the United States Navy but ran into the restrictions of the Washington and
London Naval Treaties, which placed restrictions on the sale of used warships to foreign countries. The Brazilians eventually contracted for six destroyers from the United Kingdom. In the interim, a plan to lease six destroyers from the United States was abandoned after it was met with strong opposition from both international and American institutions. Three s, based on the American , were laid down in Brazil with six minelayers, all of which were launched between 1939 and 1941. Though both programs required foreign assistance and were consequently delayed by the war, all nine ships were completed by 1944. In the 1920s, nearly all of the major warships of the Argentine Navy were obsolete; aside from
Rivadavia and
Moreno, the newest major warship had been constructed at the end of the nineteenth century. The Argentine government recognized this, and as part of holding on to their naval superiority in the region, they sent
Rivadavia and
Moreno to the United States in 1924 and 1926 to be modernized. In addition, in 1926 the Argentine Congress allotted 75 million
gold pesos for a naval building program. This resulted in the acquisition of three cruisers (the Italian-built and the British-built ), twelve destroyers (the Spanish-built and the British-built / classes), and three submarines (the Italian-built ). Chile began to seek additional ships to bolster its fleet in 1919, and the United Kingdom eagerly offered many of its surplus warships. This action worried nearby nations, who feared that a Chilean attempt to become the region's most powerful navy would destabilize the area and start another naval arms race. Chile asked for
Canada and
Eagle, the two battleships they ordered before the war, but the cost of converting the latter back to a battleship was too high. Planned replacements included the two remaining s, but a leak to the press of the secret negotiations to acquire them caused an uproar within Chile itself over the value of such ships. In the end, Chile bought only
Canada and four destroyers in April 1920—all ships that had been ordered from British yards by the Chilean government before 1914 but were purchased by the Royal Navy after the British entered the First World War—for relatively low prices.
Canada, for instance, was sold for just £1,000,000, less than half of what had been required to construct the ship. Over the next several years, the Chileans continued to acquire more ships from the British, like six destroyers (the ) and three submarines (the ).
Almirante Latorre was modernized in the United Kingdom from 1929 to 1931 at the
Devonport Dockyard. A recession and a
major naval revolt then led to the battleship's
de facto inactivation in the early 1930s. In the late 1930s, the Chilean government inquired into the possibility of constructing an cruiser in the United Kingdom, Italy, Germany, or Sweden, but this did not lead to an order. A second plan to acquire two small cruisers was dropped with the beginning of the Second World War. Soon after the
attack on Pearl Harbor, the United States attempted to purchase
Almirante Latorre, two destroyers, and a
submarine tender, probably because the Chilean Navy had a reputation for keeping its ships in top-quality condition, but the offer was rejected. During the Second World War, the three major South American navies found themselves unable to acquire major warships; they were able to do so again only after the conflict, when the United States and United Kingdom had many unnecessary or surplus warships. The war had proved the obsolete status of battleships, so the South American navies were seeking cruisers, destroyers, and submarines, yet they ran into political difficulties in acquiring anything larger than s and s. They were able to acquire them only when the
Red Scare began to strongly affect American and international politics. One of the deals reached under the
Mutual Defense Assistance Act saw six American light cruisers be evenly split between Argentina, Brazil, and Chile in January 1951. While this bolstered the navies of important South American allies of the United States, which would be
treaty-bound to assist the United States in any war, naval historian Robert Scheina argues that the American government also used the opportunity to significantly affect the traditional naval rivalry among the three countries. The warships sold unilaterally changed the naval outlook of all three nations, leading them to accept parity (as opposed to the Argentine pre-war stipulation that its fleet be equal to Brazil's and Chile's combined). The venerable dreadnoughts of South America soldiered on for a short time after the war. The US Navy's
All Hands magazine reported in a series of 1948 articles that all save
São Paulo and
Almirante Latorre were still in active service; the former had been decommissioned and the latter undergoing repairs. With the influx of the modern cruisers, frigates, and corvettes, however, the battleships were quickly sold for
scrap. The Brazilian Navy was the first to dispose of its dreadnoughts, the oldest in the world by that time.
São Paulo was sold for scrap in 1951 but sank in a storm north of the
Azores while under tow.
Minas Geraes followed two years later and was broken up in
Genoa beginning in 1954. Of the Argentine dreadnoughts,
Moreno was towed to Japan for scrapping in 1957, and
Rivadavia was broken up in Italy beginning in 1959.
Almirante Latorre, inactive and unrepaired after a 1951 explosion in its engine room, was decommissioned in October 1958 and followed
Moreno to Japan in 1959. ==Ships involved==