The Bismarcks' use of four twin turrets (the 4 × 2 configuration) was a design practice that hearkened back to the First World War. Almost all other post-1921 capital ships had triple or even quadruple turrets, which allowed for additional heavy caliber guns, while reducing the number of turrets. Fewer turrets reduced the length of the battleship's armored citadel (particularly magazine length and the armor needed to protect it) and shortened the vessel itself.