U.S. Navy Plan Emerald:
Battleships of 1920
By Mike Bennighof, Ph.D.
June 2023

Both houses of the U.S. Congress passed the Naval Act of 1916 on an overwhelming vote, despite a few voices questioning the massive cost. The Act called for construction of ten new battleships (what became the Colorado and South Dakota classes) and six new battle cruisers (the Lexington class) plus ten scout cruisers, 50 destroyers, and 67 submarines. Having received such a huge boost in spending, the Navy did not intend to stop there.

Secretary of the Navy Josephus Daniels approved the designs for the South Dakota class in July 1918, officially beginning the Bureau of Construction and Repair’s work on a new battleship to follow. This new ship would inevitably be larger and more powerful, and therefore much more expensive.

With the previous two classes, Colorado and the similar but much larger South Dakota, the designers had edged away from the principle that a ship’s armor should make her immune against her own guns. The new ship would return to that concept, and she would also have to be much faster than South Dakota, to match the purported speed of the British Queen Elizabeth class.

While South Dakota represented a great increase in size and fighting power over Colorado, some within the Navy wanted to increase her gunnery even more. A new 18-inch gun was under development for the Fiscal Year 1919 battleships, and some pointed out that the dual turret planned for these ships could be fitted in the same space as the triple 16-inch turret of the South Dakota class. Agitation to re-cast the three Fiscal Year 1919 ships (North Carolina, Iowa and Massachusetts) with the giant rifles went nowhere, though reports surfaced in the international naval press that Montana had been so fitted.

The 18-inch/48 Mark 1 had begun development but the first test unit had not been completed when the 1922 Washington naval limitations agreement halted the project, as guns larger than 16-inch caliber were now banned. It would be completed later and used for testing, first with a liner reducing the caliber to 16 inches, and then against as an 18-inch gun when such weapons were considered for the Iowa-class fast battleships.

The American 18-inch gun on her test stand.

Though the Bureau of Ordnance had great expectations for the new weapon, they would not recommend it until it had been fired. Once testing actually took place, the 18-inch gun proved a disappointment, providing only slightly more penetrative power than the 16-inch/50 Mark 2 of South Dakota. It did offer greater range, but was much heavier and the blast effects were such that it could not be mounted in a triple turret.

The Navy’s General Board met in November 1920 and January 1921 to discuss the final shape of the Fiscal Year 1920 battleships (the South Dakota class, with six ships, took up funding for both 1918 and 1919). The new ships would be laid down in 1922 and 1923, assuming continued funding for new battleships from an increasingly-reluctant Congress. The design focused on the new weapon, eight of them in four twin turrets in the classic layout of two turrets forward and two aft.

The new ship had fine lines, with greater length to help improve their speed (710 feet for the new battleship against 684 feet for South Dakota). She would be limited to the same beam (106 feet) due to the need to pass through the Panama Canal, but she would meet that beam along a greater part of her length to provide more volume for armor and machinery. The designers projected her displacement at 50,000 tons, by far the largest warship laid down by the United States up to that point (she would have been slightly larger than the Iowa class fast battleships of two decades later, but smaller than the proposed Montana class of 1939). She would have been outwardly smaller than the Royal Navy’s proposed N3-type battleships and G3-type battle cruisers, but displace more thanks to her thicker armor protection.Like previous American battleships, she would follow the “all-or-nothing” armor scheme.

To make 30 knots, the new ship would need the same massive power plant as the Lexington-class battle cruisers then under construction: sixteen boilers powering a turbo-electric drive with four shafts, putting out 180,000 horsepower or three times the output of South Dakota.

Design sketch of the 18-inch twin turret.

For the first time in an American battleship design, the secondary armament moved from the useless lightly-armored casemates to turrets. These would again be 6-inch/53-caliber guns, the same weapon used in the Omaha class cruisers, but in a newly-designed triple turret with a maximum elevation of 75 degrees to theoretically allow them to be used as anti-aircraft weapons. The new ship would have six such turrets, three on either beam, for a total of eighteen secondary guns. She would also carry nine five-inch anti-aircraft guns in shielded deck mounts.

At the Washington talks, the American hosts probably did the least well of all the negotiating teams. In addition to Washington, the Americans also gave up all six South Dakota class ships. The FY 1920 battleships had not been ordered, and don’t appear to have been used as bargaining chips at the talks in the same manner as the British deployed their equally-vaporous N3 type super battleships. The 1920 battleship quietly disappeared into the design archives.

That’s not the situation in our Red-Orange alternative history. Four of the 1920 battleships appear in Great War at Sea: U.S. Navy Plan Emerald, and four more in U.S. Navy Plan Orange. That alternative history posits an early end to the First World War thanks to a negotiated settlement, and so the United States does not participate Over There. That in turns means that there is no pause in battleship construction as happened in our real history, and so the Colorado class are laid down in 1917 as initially planned, all six of the South Dakota class in 1918, and the first four of the new battleships (here called the Oregon class) in 1919 to enter service in 1922.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and NASA Journalist in Space finalist, he has published a great many books, games and articles on historical subjects; people are saying that some of them are actually good. He lives in Birmingham, Alabama with his wife and three children. He misses his Iron Dog, Leopold.

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