The Montana-class battleships are one of America’s greatest “what ifs” in naval history—a look into an era where battleship design reached the absolute limit of technology, only to be overthrown by the advent of airpower and the aircraft carrier. Designed in World War II to replace the Iowa-class ships, the Montanas were to be the biggest and best ships ever produced by the U.S. Navy. Their tale is one of great vision, advanced design, and eventual obsolescence.
While the Iowa-class emphasized speed to maintain pace within fast carrier groups, the Montana-class went back to the concept of heavy armor and ruggedness. No longer constrained by pre-war treaty limitations, designers learned from earlier war experiences to design ships that could withstand punishment and deliver crushing firepower.
Fully loaded, a Montana-class battleship would have displaced over 70,000 tons, with a top speed of around 28 knots. Slightly slower than the Iowas, these giants traded speed for survivability, armored strength, and formidable weaponry.
Armor defined the Montanas. No external vertical belt like on previous ships of the Iowa and South Dakota classes, whose internal belts had been problematic to repair while absorbing hits.
The belt itself was 16.1 inches thick and supported by special treatment steel, and at a 19-degree incline to provide maximum shielding. At close range, it offered up to 18 inches of effective armor with even greater shielding at longer ranges because descending shells struck at steeper angles.
To guard against plunging shells—those that struck the water short of the hull—the Montanas also featured a lower belt: 8.5 inches above the magazines and 7.2 inches above machinery spaces, extending down to the triple bottom. This separation between upper and lower belts created a protective balance against both heavy artillery and underwater attacks, reflecting lessons learned through decades of naval experimentation.
Horizontal protection was equally impressive. Three armored deck layers shielded critical areas: a 2.25-inch weather deck to pre-detonate incoming fuzes, a 7.05-inch main deck over the citadel, and a one-inch splinter deck to catch fragments. Combined, this provided nearly 10 inches of horizontal armor—far superior to earlier U.S. battleships and a strong defense against bombs or high-angle shellfire.
Main gun turrets and barbettes were armoured to the same standard. Turret faceplates were 22.5 inches thick, three inches more than the Iowas’, with sloped and thickened roofs and sides. Barbettes—the tunnel-like supports to the turrets—were 18 to 21.3 inches thick so that the ship’s main armament should be highly protected.
Through these defenses, the Montana-class could, in theory, keep firing even while taking fierce bombardment and retain combat power in the types of close-in artillery duels into which battleships were designed.
Underwater protection also received careful thought. A torpedo defense system featured four layers of voids between the inner bulkhead and outer hull. The two outer layers were liquid-filled to absorb explosive energy, while the inner layers remained empty to dissipate any remaining force.
The Montana-class’s massive size allowed this system to be deeper and more effective than on earlier battleships, offering a significant safeguard against torpedo attacks. Ultimately, the Montana-class is a testament to vision and innovation—a concept of naval force never realized but demonstrating the apex of battleship design and the wisdom of an evolving age.