The Amazonian Navy had not built any light cruisers for almost 20 years. Thee seven heavy cruisers built in the 1930's used up all the budget allowed for the type. The three Enchesimargos class had cost almost the same as two of the Phillipis class battleships. Then again the Phillipis class battleships would not have been alone, patrolling out on the Trade Routes. They would have had all sorts of escorts with them. The need for more small cruisers was at a premium requirement stage. What type of cruiser was the conundrum. The Amazonian arsenal did not have an intermediate sized Dual Purpose (4.5"-5.3") weapon. They were using twin and single open 4" mountings or the 4" BD mounting fitted to the battleships and battlecruisers. It was decided a cruiser of about 500 feet could fit five twin 4" mountings in an anti-aircraft cruiser role. Ten were ordered in 1937 for completion in late 1939 to 1942 (1939x2, 1940x3, 1941x3, 1942x2). A further six were ordered in 1940 after two were lost early in European waters (1 at Dunkirk, 1 at Norway.).
The batch two ships had the same basic layout, but had 40mm Bofors replacing the 2 pounder and 20mm, the torpedoes removed, updated bridge layouts fore and aft, more and better radar and directors. The biggest change was replacing the open backed twin 4" mountings with the twin BD 4" turrets. One of the early complaints in the Batch One ships was that splinters would kill lots of the 4" guns crew and leave the guns performing slower from lack of crew. The BD turret stopped that. They added a bit more weight, but the change of layout saved a bit balancing it all out. One other thing set them apart from the Batch One ships, they were fitted with Hedgehog mortars on either side of the bridge and had an asdic mounting under the bow.
The whole class was very active during the war. Their AA capabilities put them into the danger spots, and they suffered for it. Six out of the 16 were lost. As noted earlier one was bombed and lost at Dunkirk, One was sunk by the Scharnhorst and Gneisenau in defence of the Glorious in the Norwegian Campaign, one was mined in the Med with Force K, one was bombed south of Crete escorting troops taken off Crete. Only two were lost in the Pacific. Whenever they were away from the protection of the Fleet they were vulnerable. One was sunk in the battles around Guadalcanal, the other in the taking of the Gilbert Islands, torpedoed by a submarine. At the end of the war the earlier 6 remaining batch one ships were offered for sale and sold to minor powers looking for a cheap 'cruiser' for their navies.
The remaining four batch two ships were kept and after Korea they were to be upgraded as necessary to get them through to the end of the 1960's.
