Veinticinco de Mayo - class cruiser The two " Veinticinco de Mayo " - class heavy cruiser s served in the Argentine Navy through World War II . They were the only post - Washington Naval Treaty heavy cruisers built for a South American Navy . Both ships of the class were built in Italy by the OTO company , and commissioned into the Argentine Navy in 1931 . Design . The " Veinticinco de Mayo " design was derived from the Italian " Trento " class , identifiable by the closely paired main guns , similar to the last batches of the " Condottieri " class cruisers . The ships were smaller than the original , and carried significantly less armour . They had a clean and simple design , with a length - width ratio of almost 10 : 1 . Three twin turrets were mounted with an elevation of 46 degrees for firing . They were not the first Argentinian cruiser class bought in Italy , as four Garibaldi - class armoured cruisers were brought into service 30 years before . Armament . The main 190 mm ( 7 . 5 inch ) guns were designed especially for this class for greater stability ( the Trento - class carried 203 mm ( 8 inch ) guns ) . This could have been a quite powerful gun , but no documents about its characteristics are available in Italian or Argentinian archives . The guns had single mounts to simplify construction , and could fire a 90 kg ( 200 lb ) shell up to 23 km ( 30 , 000 yards ) . Despite this reduction in size and weight , they were still too heavy , so the number of turrets were reduced from four to three . In most respects the resulting vessel was similar in profile to the British " York " class cruiser . The secondary armament was also a new design , similar to standard 100 – 102 mm guns of the time . It consisted of twelve 102 mm ( 4 inch ) DP guns , firing a 13 . 5 kg ( 30 lb ) shell , all in twin mounts . This was an unusual arrangement for Italian heavy cruisers , which generally carried only four to eight of these weapons . However to counter the additional weight , gun shields were removed , which adversely affected their operability in bad weather conditions . Unusually , the torpedo tubes were in fixed mounts amidships firing abeam , which caused problems in aiming effectively . Light anti - aircraft artillery consisted of six Vickers - Terni 40 / 39 mm guns , all in single mounts , on the aft part of the superstructure . These guns were among the first automatic heavy weapons , firing 100 - 130 rounds per minute , but were of poor reliability . Though single mounts were simpler and more reliable , they offered poorer fire concentration . The Royal Navy used similar weapons in quad or even octuple mounts . Finally , a catapult launcher for seaplanes was placed over the fore deck . Armour was within the standard for light rather than heavy cruisers . A 70 mm ( 2 . 75 inch ) armoured belt was fitted from the first to the last main turret . 60 mm ( 2 . 33 in ) was used for the command turret . 50 mm ( 2 in ) was used for turrets and barbettes . Only 25 mm ( 1 inch ) was provided for armoured deck and above aft machinery . Post - war refit . After World War II the ships were modified to improve their stability by reducing weight . The powerful twin 102 mm gun batteries were replaced with six Bofors 40 mm gun s , one for each twin mount , drastically reducing the secondary armament . Another four Bofors replaced the six Vickers AA guns . US Mk . 53 radar directors were also installed to improve the effectiveness of anti - aircraft fire . The gain in stability , with several tons removed for each 102 mm gun , was somewhat offset by the addition of radar installations to the superstructure and masts . The aircraft catapult launcher was moved from the fore deck to mid - ships . Units . Despite Argentina ' s declaration of war on 27 March 1945 , neither vessel played a role in the conflict . The ships proved popular with the Argentine Navy , until they were superseded by two Brooklyn class cruiser s acquired in 1951 . " Veinticinco de Mayo " C - 2 . Named after the 25th of May , Argentina ' s National Day . Built by OTO La Foce , Italy , laid down 12 October 1927 , launched 28 September 1929 , completed 18 July 1931 . Decommissioned 27 June 1961 . " Almirante Brown " C - 1 . Named after Admiral Guillermo Brown , father of the Argentine Navy . Built by OTO Livorno , laid down 27 November 1927 , launched 11 August 1929 , completed 11 July 1931 . Decommissioned 27 June 1961 . Further plans . Argentina originally planned to acquire three of the class , but were limited to having only two built . They would turn to the United Kingdom for their next cruiser , acquiring the " La Argentina " in 1938 .