The primary changes were the adoption of a more powerful 12 in (305 mm)/50 caliber Mark 7 gun, addition of a sixth twin-gun turret and improved armor protection, including the first use of a torpedo bulkhead on American battleships.

Both vessels were deployed to British waters after the United States entered World War I in April 1917 to reinforce the Royal Navy's Grand Fleet.

Wyoming and Arkansas were heavily modernized in the mid-1920s, receiving more efficient oil-fired boilers to replace their old coal-fired models, thicker deck armor to protect against plunging fire, anti-torpedo bulges to increase their resistance to underwater damage, and anti-aircraft guns to defend against aerial attacks.

The London Naval Treaty of 1930 mandated that Wyoming be demilitarized; she accordingly was converted into a training ship, with half of her main battery turrets, belt armor, and anti-torpedo bulges removed.

After the United States entered World War II, Arkansas was used to escort convoys to North Africa.

Wyoming meanwhile continued as a training ship, being modified further in 1944 to include the various types of anti-aircraft guns that trainees would operate in the fleet.

On 26 August, the Secretary of the Navy, Victor Metcalf, issued a request for eight- and ten-gun battleships armed with the 14-inch weapons to the Bureau of Construction and Repair (C&R).

Some officers at the Newport Conference had advocated placing them in the superstructure, but the heavy 5-inch (127 mm) guns used by the Navy would have added excessive top weight.

A new protection scheme for the funnels was devised, after the Russian experience at the Battle of Tsushima three years before had highlighted the risk of a destroyed exhaust system.

They had a full length flush deck, which improved sea-keeping and the ability to work the secondary guns in heavier seas.

Steam was provided by twelve mixed oil and coal-fired Babcock & Wilcox boilers, which were trunked into two closely spaced funnels amidships.

[12] As was standard for capital ships of the period, they carried a pair of submerged 21-inch (530 mm) torpedo tubes in the hull on the broadside.

[10] They were equipped with the Mark III Bliss-Leavitt design, which carried a 218 lb (99 kg) warhead and had a range of 4,000 yd (3,700 m) at a speed of 26.5 kn (49.1 km/h; 30.5 mph).

[13] The main armored belt, which was 8 ft (2.4 m) high, was 11 in (280 mm) thick over the central portion of the ship, where it protected the ammunition magazines and machinery spaces.

These were deemed important because during the Russo-Japanese War, three years before, Russian battleships had had their uptakes damaged, which ducted the boiler smoke into the ship rather than out through the funnels.

During and shortly after World War I, the horizontal armor of the ships was improved, including the roofs of the conning tower and the gun turrets.

These boilers were much more efficient than the coal-fired models the ships had been completed with, and they allowed a significantly greater cruising radius of 11,000 nmi (20,000 km; 13,000 mi).

The ships were also fitted with anti-torpedo bulges, which improved their underwater defense and also provided additional oil storage capacity.

[21] New fire control radars were also installed; these modifications allowed Wyoming to train anti-aircraft gunners with the most modern equipment they would use while in combat with the fleet.

The ships took part in the normal routine of training and fleet maneuvers off the east coast of the United States and in the Caribbean, interspersed with periodic maintenance.

After the United States declared war on Germany on 6 April 1917, Wyoming, along with the rest of Battleship Division 9 (BatDiv 9), steamed to Britain to reinforce the Royal Navy's Grand Fleet, stationed in Scapa Flow.

Arkansas initially remained in the United States, training gun crews for the expanding wartime fleet.

During this time, the ships made a tour of Central and South American countries, culminating in a visit to Valparaiso, where they took part in a naval review for the Chilean president.

She supported the replacement of Canadian troops by American ones maintaining the occupation of Iceland in July 1941 as an escort for the troopship convoys.

Arkansas, meanwhile, continued in front-line service during the war, first as an escort to convoys to North Africa, and then as a shore bombardment vessel.

She supported the landings at Normandy in June 1944, shelling German positions at Omaha Beach, before bombarding Cherbourg later in the month.

[20][22] With the end of the war in September 1945, Arkansas was employed with Operation Magic Carpet, repatriating American soldiers in the Pacific.