These cruisers are the most direct copy of any Japanese ship anywhere in the world. As a matter of fact, they hardly look like anything the US Navy ever build before or after them.
However, they were not originally concepted to be a copy or answer of the Japanese Mogami class. At first, their design was to be of rather usual Heavy Cruiser scheme. However, the restrictions of the London Naval Treaty forced the Navy to projet another design. This was only well; for the Japanese had put out a type of ship which appeared to be in need of a counter, the Mogami class, with five triple 152mm turrets. As the Navy had already thought about using 152mm instead of the 203mm, because the former was having a faster rate of fire and could be mounted in greater numbers, leading to a higher "lead-per-minute" output, the Brooklyns received an extensive redesign.
The general outline of the gun mounts as undoubtely copied from the Japanese Takao class heavy cruisers - the armament was taken from the Mogami class. The class was unique in different respects, as they were the first flushdeck cruisers, which was necessary because the ships were to receive a hangar in the stern, belowdecks.
This class had also an interesting level of differences between its member ships. St. Louis and Helena received twin mounts for their secondary armament and the later 127mm L/38, while the earlier ships kept their 127mm L/25 in open mounts. Furthermore, the first seven ships had a highly different superstructure layout.
The vessels saw extensive wartime service. Due to the large size of the class (nine ships), I am unable to detail all actions this class fought in, or all campaigns they participated in. However, it can be said that Boise was in the far-east at war's start, but was recalled. Helena fought in the battles of Cape Esperance and First Guadalcanal, and Honolulu at Tassafaronga, where she was the only undamaged US cruiser after the fight.
Honolulu, Helena and St. Louis formed the core of Rear Admiral Walden A. Ainsworth's Bombardement Group, and were frequently seen shelling Japanese airfields in the Solomons. The cruisers fought in one, respectively two battles. At Kula Gulf, Helena was torpedoed and sunk, with 1155 survivors, rendering her unable to participate at the Battle of Kolombangara, where St.Louis and Honolulu fought together with HMNZS Leander, and as the two others, suffered torpedo hits.
The only other wartime loss, besides Helena, was Phoenix,
which sank in 1982 due to torpedos from HM submarine Conqueror, as
Argentine General Belgrano. Ironically, the only modern means of
combat in this battle was the British submarine, for the Belgrano's
escorts, and the torpedoes which sank her, were all of WW2 vintage.
15 x 152mm L/47 in five triple turrets1
8 x 127mm L/25 in open mounts, four on each side2
8 x 28mm
12 x 20mm.
15 x 152mm L/47 as above
8 x 127mm L/38 in twin turrets, two on each side
28 x 40mm L/56
20 x 20mm
Standard: 9700 tons
CL-49 + 50:
Standard: 10600 tons
Full: 13300 tons
Length: 185.4 meters
Beam: 18.8 meters
Draught: 6.9 meters
Height (Mast): 35.4 meters
Crew: 868 peace, CL-50 war: 47/1276
Speed: 32.5 knots
||4 floatplanes in below-decks hanger.|
CL-49 St. Louis