Marinha Do Brasil was the second best navy in South America in 1939, below the Argentinian Armada but forward of the Chilean Navy. She started the South American dreadnought race before ww1 by ordering the Minas Gerais and late the Rio de Janeiro which was later requisitioned as HMS Agincourt. But in 1939 the navy was largely obsolescent. Nevertheless, in 1942, U-boats attacks on the South Atlantic reached such a level that on 22 August 1942, Brazil declared war to the Axis powers.
Indeed, Italian submarines, operating from Bordeaux, also roamed the south Atlantic. One was sunk by Brazilian vessels, as well as twelve U-Boats while the Brazilians lost just one auxiliary vessel and 32 merchant ships. In 1944 the Navy has been well reinforced by the US Navy, which installed naval bases and eventually the South Atlantic Command, transferred 8 DET-class escort destroyers (Beberibe class) and 16 PC-boat submarines-chasers (Gioana class). The British Navy transferred also six armed trawlers. Brasil also built the Marcilio Dias and Acre class destroyers at Rio de Janeiro’ Ilha das Cobras shipyards. These ships were largely inspired by American destroyers and equipped with North American artillery, firing systems and equipment but only a few really were completed before the war ended.
In all, Brazil did her fair share of operations in the battle of the Atlantic. The contribution was considerable and successful given the number of convoys protected: 614 wartime convoys, representing 3,164 merchant and transport troop ships bound to UK of Gibraltar, also supporting the Brazilian expeditionary force taking part in the campaign of Italy. 66 U-boats were attacked by Brazilian ships, twelve U-boats were sunk for the loss of just one auxiliary ship, the Bz Vital de Oliveira. The cruiser Bahia and corvette Camaquã were also lost, the first because of an accidental explosion and the second in a storm.