Shipboard casemate guns were partially rendered obsolete by the arrival of "all-big gun" battleship, pioneered by in 1906, but were reintroduced as the increasing torpedo threat from destroyers forced an increase in secondary armament calibre. Many battleships had their casemates plated over during modernization in the 1930s (or after the Attack on Pearl Harbor, in the case of US vessels) but some, like carried them to the end of World War II. The last ships built with casemates as new construction were the American s of the early 1920s and the 1933 Swedish aircraft cruiser . In both cases the casemates were built into the forward angles of the forward superstructure (and the aft superstructure as well, in the Omahas).