Omaha Class Cruisers

The Omaha class cruisers were the only American cruisers to be ordered during the First World War, although they weren't completed until the early 1920s. Although they were somewhat outdated even when they were completed they remained in service into the Second World War, where they were used in the south Pacific, the Aleutians and the Atlantic.

The US Navy had stopped building cruisers ten years before work began on the Omaha class, but there were some clear links to the earlier designs. The previous Chester or Salem class of 1905 were flush decked four funnelled cruisers, with very little superstructure, and a clear resemblance to the famous flush-decked destroyers. The big different was size - the Chester class ships had a displacement of 3,750t, were 423ft 2in long and 47ft 1in wide. The Omaha class cruisers were twice as heavy, at, 7,050t normal displacement, and were 555ft long and 55ft 5in wide, so were much more substantial vessels.  

USS Omaha (CL-4) aground in the Bahamas, 1937
USS Omaha (CL-4)
aground in the
Bahamas, 1937

The US Navy had spent most of the intervening decade arguing about the type of cruisers they needed, producing a wide range of designs from very light scout cruisers up to massive battlecruisers. The Omaha class cruisers were ordered as part of the 1916 naval programme, which also included a large number of destroyers and fast cruisers.

The Omaha class ships were originally designed to carry ten 6in guns in a rather unusual configuration. Two were to be carried in the waist and the remaining eight in individual casemates. These were to be carried on either side of the fore and aft superstructures, with two levels of casemates in each position. The aim was to maximise forward and aft firepower, with four guns being able to fire directly ahead or behind the ship. Originally five guns could fire on the broadside, but this was reduced to four when the waist guns were deleted early in the design process. The casemated guns also had a limited arc of fire, so targets that weren't directly ahead or behind the ships could only be hit by two. They were designed on the assumption that cruisers would either be chasing weaker enemies or being chased by stronger foes, and so would need to concentrate their firepower fore and aft. Spotting was to be performed by aircraft, and they were designed to use a fixed catapult on the quarterdeck, but they were built with trainable catapults in the waist.

USS Milwaukee (CL-5), Tacoma, Washington, 1923
USS Milwaukee (CL-5), Tacoma, Washington, 1923

This layout soon came in for criticism. After the American entry into the First World War the US Navy worked alongside the Royal Navy. Most contemporary British cruisers had more powerful broadsides, and turret mounted guns fore and aft, with a wider arc of fire than the casemated guns of the Omaha class. To compensate the Omahas were given two twin 6in gun mounts, carried fore and aft. This meant that they could fire six guns at targets directly ahead or behind, four at targets off to one side (two in casemates and two in the mounting), or a broadside of eight guns. Even this design wasn't without its flaws - the lower pair of rear casemates turned out to be too close to the water, and were thus very wet in action and by the start of the Second World War they had been removed from the surviving ships. The next American cruisers, the Pensacola class, carried their guns in superfiring turrets on the centre line, a much more flexible layout.

USS Cincinnati (CL-6) at New York, 22 March 1944
USS Cincinnati (CL-6)
at New York,
22 March 1944

The number of torpedo tubes was also increased. Originally they had been designed with twin banks of 21in tubes. They were built with the twin bank and with two triple banks of torpedo tubes. In service the twin tubes were removed, so by the Second World War they had six 21in torpedo tubes in two triple banks. The secondary armament was also changed, generally by removing guns to save weight. They caught also lay mines.

Visually the Omaha class cruisers greatly resembled the flush-deck destroyers, with four funnels, a small rear superstructure and larger forward superstructure. Their machinery used the unit system, with twelve boilers in four boiler rooms, two forward and two aft. The turbine rooms were between the fore and aft boiler rooms.

The boilers and turbines installed varied depending on the builders. Production was split between three builders - Todd of Seattle, Cramp of Philadelphia and Bethlehem of Quincy.

CL-4 to CL-6 were built by Todd. They used Yarrow boilers and Westinghouse turbines, and shorter range cruising turbines.

CL-7 and CL-8 were built by Bethlehem, and used Yarrow boilers, Curtis turbines and shorter range cruising turbines.

USS Raleigh (CL-7) anchored
USS Raleigh (CL-7)
anchored

CL-9 to CL-13 were built by Cramp. They had White-Forster boilers, Parsons turbines and longer range cruising turbines.

For their size the Omaha ships were given powerful engines, which gave them a top speed of 34-35kts. They were designed to have an endurance of 10,000nm at 10kts, but rarely managed to achieve this.

Service Records

Omaha (CL-4) served in the Atlantic for most of her career, taking part in the Neutrality Patrol before the American entry into the war and the campaign against Axis blockade runners afterwards. She also supported Operation Dragoon, the invasion of the south of France.

Milwaukee (CL-5) was in the Pacific from 1928-1940, then moved to the Neutrality Patrol in the Atlantic. After the American entry into the war she served in the Caribbean and briefly in the Pacific, before returning to the Atlantic from 1942-44. In 1944 she was given to the Soviet Union where she served as the Murmanskuntil 1949.

Band of USS Detroit (CL-8) 'crossing the line'
Band of USS Detroit (CL-8) 'crossing the line'

USS Richmond (CL-9) in Panama Canal, 1925
USS Richmond (CL-9) in Panama Canal, 1925

Cincinnati (CL-6) served in the Atlantic, the Pacific and the Asiatic Fleets between the wars, but from 1941-45 served in the Atlantic. Like the Omaha she took part in Operation Dragoon.

Raleigh (CL-7) served in the Atlantic and Pacific before the war. She was based at Pearl Harbor from 1938 and was hit by Japanese torpedoes during the attack on Pearl Harbor of 7 December 1941. After her repairs she served in the Aleutians and the North Pacific.

USS Marblehead (CL-12) side view
USS Marblehead (CL-12)
side view

Detroit (CL-8) was at Pearl Harbor. She served in the Pacific for the rest of the war, operating in areas as far apart as the Aleutians and the South East Pacific.

Richmond (CL-9) served as flagship of the Scouting Force, then the Light Cruiser Division. She then served on the China Station (1927), the US East Coast (1934-37) and in the Pacific (1937-1940). She then joined the Neutrality Patrol in the Atlantic. After the US entry into the war she escorted convoys in the Pacific (1941-43) then moved to the North Pacific, where she fought in the Aleutians campaign.

Concord (CL-10) served in the Atlantic from 1925-31, then with the Scouting Force and the Battle Force. After the American entry into the war she served on convoy escort duty in the south-east Pacific, then in the Aleutians from April 1944 onwards.

Trenton (CL-11) served in the South Pacific from 1942-44 then in the Aleutians, where she remained for the rest of the war.

Marblehead (CL-12) was in the Philippines when the Japanese attacked and was involved in the disastrous campaign in the Dutch East Indies. She was badly damaged by Japanese bombs but reached Ceylon. After being repaired she served in the Atlantic, then supported Operation Dragoon, the invasion of the south of France.

USS Memphis (CL-13) in the South Atlantic, 1941-42
USS Memphis (CL-13)
in the South Atlantic,
1941-42

Bow View of USS Trenton (CL-11)
Bow View of USS Trenton (CL-11)

Memphis (CL-13) initially served in the Atlantic, but was also deployed in Europe and Australasia. She was based in the Pacific from 1928 and in Alaska from 1939-41. She then became part of the Neutrality Patrol in the Atlantic before spending most of the Second World War in the South Atlantic. During 1945 she was the flagship, Commander USN Forces in Europe, based in the Mediterranean.

Displacement (standard)

7,050t

Displacement (loaded)

9,508t

Top Speed

34kts

Range

10,000nm at 10kts (design)
8,460nm at 10kts (actual)

Armour – deck

1.5in

 - belt

3in

Length

555ft 6in

Width

55ft 5in

Armaments (as built)

Twelve 6in/53 guns
Two 3in/50 AA guns
Ten 21in torpedo tubes (two triple and two double mountings)

Crew complement

459

Ships in Class

Fate

CL-4 Omaha

Stricken 1945

CL-5 Milwaukee

To USSR 1944

CL-6 Cincinnati

Sold 1946

CL-7 Raleigh

Sold 1946

CL-8 Detroit

Sold 1946

CL-9 Richmond

Stricken 1946

CL-10 Concord

Sold 1947

CL-11 Trenton

Sold 1947

CL-12 Marblehead

Stricken 1945

CL-13 Memphis

Stricken 1946

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How to cite this article: Rickard, J (1 January 2014), Omaha Class Cruisers, http://www.historyofwar.org/articles/weapons_omaha_class_cruisers.html

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