Eagle retained useful protection from the battleship hull. She no longer needed the massive barbettes intended for 14-inch guns, and armour from the original upper belt was moved to protect the waterline. The resulting belt was about 4.5 inches thick while the ship's internal spaces and topweight were reorganized for aviation. This protection helps explain her ability to absorb repeated wartime damage and continue operating, although no armour scheme could save her from four broadside torpedo hits in 1942.
Notable Point · 23:53-24:28
How battleship armour was rearranged for the carrier conversion
Removing Almirante Cochrane's 14-inch barbettes allowed armour from the battleship layout to be redistributed into roughly 4.5 inches of waterline protection for Eagle.