Key point: A new age of warfare had begun.
The U.S. Navy’s most powerful battleships were never actually built.
The five Montana-class battleships, leviathans designed to dwarf even the giant Iowa-class battleships, were authorized for construction but never built, victims of the ascendance of naval aviation. Nearly as large as a modern supercarrier the Montana-class, like all battleships, was made obsolete by the success of the aircraft carrier.
In the late 1930s, the U.S. government, recognizing the deteriorating world situation, sought to rebuild U.S. naval power. The crash of the stock market in October 1939, as well as the Washington and London naval treaties, had slowed the growth of the U.S. Navy and reduced its tempo of peacetime operations. By 1940, however, with fighting raging in Asia and Europe, it was clear the United States needed to beef up its defensive capability to deter attack—or to prosecute a war if it were dragged into conflict.
In 1940, the federal government authorized the famous “Two Ocean Navy” capability that laid the groundwork for the wartime U.S. Navy that followed. One set of authorized ships: five Montana-class battleships to complement the Iowa-class battleships. America’s shipyards would split the work between the Philadelphia Navy Yard (two), New York Navy Yard (two), and Norfolk Navy Yard (one).
Numerous proposals were floated for the Montana-class ships, though they all had one thing in common: they were considerably larger than the Iowas. The Iowa class battleships were 860 feet long, displaced 58,000 tons fully loaded, and featured nine 16”/50 caliber main guns. Secondary armament was in the form of twenty 5”/38 caliber dual-purpose guns capable of firing on targets in the air, on land, and at sea. Speed would have been 28 knots, slower than the Iowa-class’ 33 knot top speed.