Anti-Air Armament Development of U.S. Aircraft Carriers
by Keith E. Allen

LEXINGTON Class ---No light AA at completion. ---.50 cal machine guns added beginning in mid-1930s; by 1936 Lexington had 28 and by 1940 she had 32. I'm not sure how many Saratoga had. --- In about 1940 four 3in/50 were added; these guns were fitted on a number of ships about this time as an interim stand-in for the 1.1. A few .50s were removed. ---By 7 December 1941 all 3-inchers were replaced by 1.1 quads. ---Armament was significantly increased early in the war. At the time of her loss Lexington had twelve quad 1.1s, 32-20mm, and 28-.50 cal. Saratoga at this time had nine 1.1 quads, 32-20mm, and no .50 caliber remaining. ---In May 1942 Saratoga's 5in/25s were replaced by sixteen 5in/38. ---Saratoga, late 1942: Nine quad 40mm, 52-20mm. All 1.1s were gone. ---In late 1943-early 1944 32 40mm were added. ---Saratoga, end of war: 25 quad 40mm (I believe the heaviest 40mm armament of any ship), only sixteen 20mm.

RANGER Ranger completed with eight 5in/25 and a surprisingly large battery of forty .50 cals. By September 1941 she had six quad 1.1s and 24-.50 cal. By January 1943 she had six quad 40s and 46-20mm.

YORKTOWN Class ---Completed with four 1.1 quads, 24-.50 cal. ---Midway: Yorktown had 24-20mm, retaining the 1.1s (.50 cal presumably removed). Enterprise had 34-20mm in addition to 1.1s. Hornet had 24-20mm, replacing the .50 cals. ---Hornet, after Midway: A fifth 1.1 quad was added. By August she had 32-20mm. She was probably in about this configuration when she was sunk at Santa Cruz on 26 October 1942. ---Enterprise, August 1942: Five 1.1 quad, 38-20mm. ---November 1942: Four quad 40mm, 46-20mm. One 1.1 quad apparently retained; I'm not sure when it was removed. ---October 1943: 40-40mm (six quad, eight twin), 53-20mm (48 single, one twin, one experimental triple). ---End of war: 54-40mm (11 quad, five twin), 32-20mm (sixteen twin).

ESSEX Class Original armament for the early ships was about eight quad 40mm and 46-20mm. At the end of the war, 40mm armament ranged from ten quads to eighteen quads, with eighteen the most common. 20mm armament at the end of the war varied widely, from 35 guns in Hornet to 113 in Shangri-La; the average appears to have been about 60. Lexington and Wasp had some new quad .50 cals at the end of the war. To illustrate the progression in armament in one Essex, here are some figures from the Leeward-series booklet on the second Yorktown: ---At completion, April 1943: eight quad 40s, 46-20mm ---September 1943: ten quad 40s, 55-20mm ---June 1944: seventeen quad 40s, 55-20mm. The 20mm armament was later increased to 61.

INDEPENDENCE Class CVLs The original light AA armament was 24-40mm (two quad, eight twin) and 22-20mm. Subsequently some 20mm were replaced by twin 40mm. By the end of the war these ships apparently had 26 to 28-40mm, and between 4 and 22-20mm. Considering that the CVLs, uniquely among war-built U.S. large combatants, had no 5in/38s, this is not a particularly impressive AA armament. Escort Carriers I will just give figures for the most numerous type, the Casablanca class. At completion they had four twin 40mm and 12-20mm. At the end of the war the standard battery was eight twin 40mm and 20-20mm. They also, unlike the CVLs, had one five-incher. These ships were proportionately much better armed than the CVLs.