World War II: USS Illinois (BB-65)

USS Illinois (BB-65) under construction at Philadelphia Navy Yard, 1945. Photograph Courtesy of the US Navy

USS Illinois (BB-65) was a battleship that was laid down during World War II (1939-1945) but never completed. First proposed as a ship of the massive Montana-class of battleship, Illinois was re-ordered in 1940 as the fifth vessel of the US Navy's Iowa-class. As work commenced, the US Navy found that it had a more pressing need for aircraft carriers than battleships. This led to efforts to convert Illinois into a carrier. The resulting designs proved impractical and construction resumed on the battleship but at a slow speed. In early August 1945, with Illinois only 22% complete, the US Navy elected to cancel the ship. Some debate ensued regarding completing the hull for use in nuclear testing, but the cost proved prohibitive and the decision was made to break up what had been built.

A New Design

In early 1938, work commenced on a new battleship design at the request of US Navy General Board head Admiral Thomas C. Hart. At first conceived as a larger version of the earlier South Dakota-class, the new battleships were to mount twelve 16" guns or nine 18" guns. As the design was revised, the armament changed to nine 16" guns. In addition, the class' anti-aircraft complement underwent several evolutions with the majority of its 1.1" weapons being replaced with 20 mm and 40 mm guns. Funding for the new ships came in May with the approval of the Naval Act of 1938. Designated the Iowa-class, construction of the lead ship, USS Iowa (BB-61), was assigned to the New York Navy Yard. Laid down in 1940, Iowa was to be the first of four battleships in the class.

Fast Battleships

Though hull numbers BB-65 and BB-66 were originally slated to be the first two ships of the new, larger Montana-class, the passage of the Two Ocean Navy Act in July 1940 saw them re-designated as two additional Iowa-class battleships named USS Illinois and USS Kentucky respectively. As "fast battleships," their 33-knot speed would allow them to serve as escorts for the new Essex-class carriers that were joining the fleet. 

Unlike the preceding Iowa-class ships (IowaNew JerseyMissouri, and Wisconsin), Illinois and Kentucky were to employ all-welded construction which reduced weight while increasing hull strength. Some debate was also given as to whether to retain the heavy armor scheme initially intended for the Montana-class. Though this would have improved the vessels' protection, it would also have greatly extended construction time. As a result, standard Iowa-class armor was ordered. One adjustment that was made in the design was to alter elements of the armor scheme to improve protection against torpedo attacks. 

USS Illinois (BB-65) - Overview

  • Nation: United States
  • Type: Battleship
  • Shipyard: Philadelphia Naval Shipyard
  • Laid Down: December 6, 1942
  • Fate: Scrapped, September 1958

Specifications (Planned)

  • Displacement: 45,000 tons
  • Length: 887.2 ft.
  • Beam: 108 ft., 2 in.
  • Draft: 28.9 ft.
  • Speed: 33 knots
  • Complement: 2,788

Armament (Planned)


  • 9 × 16 in./50 cal Mark 7 guns
  • 20 × 5 in./38 cal Mark 12 guns
  • 80 × 40 mm/56 cal anti-aircraft guns
  • 49 × 20 mm/70 cal anti-aircraft cannons


The second ship to carry the name USS Illinois, the first being an Illinois-class battleship (BB-7) commissioned in 1901, BB-65 was laid down at the Philadelphia Naval Shipyard on January 15, 1945. The delay in the start of construction came as a result of the US Navy putting the battleship on hold following the Battles of the Coral Sea and Midway. In the wake of these engagements, the need for additional aircraft carriers became apparent and these types of vessels took priority in American shipyards.

As a result, naval architects began exploring plans for converting Illinois and Kentucky (under construction since 1942) into carriers. The finalized conversion plan would have produced two vessels similar in appearance to the Essex-class. In addition to their aircraft complement, they would have carried twelve 5" guns in four twin and four single mounts. Assessing these plans, it was soon determined that the converted battleship's aircraft complement would be smaller than the Essex-class and that the construction process would take longer and cost more than was practical. 

Due to this, the decision was made to complete both vessels as battleships but very low priority was given to their construction. Work moved forward on Illinois in early 1945 and continued into the summer.  With victory over Germany and the impending defeat of Japan, the US Navy ordered construction on the battleship to cease on August 11. Struck from the Naval Vessel Registry the next day, some thought was later given to using the vessel's hulk as a target for nuclear testing. When the cost of completing the hull to permit this use was determined and concluded to be too high, the decision to break up the vessel on the ways was made. Scrapping of Illinois' incomplete hull commenced in September 1958.      

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Your Citation
Hickman, Kennedy. "World War II: USS Illinois (BB-65)." ThoughtCo, Aug. 26, 2020, Hickman, Kennedy. (2020, August 26). World War II: USS Illinois (BB-65). Retrieved from Hickman, Kennedy. "World War II: USS Illinois (BB-65)." ThoughtCo. (accessed February 9, 2023).