The J3 class battlecruiser was a design study conducted during the Royal Navy's 1921 Fleet modernization programme. As a follow-on to the Admiral-class battlecruiser, the J3 class incorporated all the lessons learned from the First World War, specifically the battle of Jutland. The design was seen as an improvement to the Admiral class by virtue of its heavier and improved armouring scheme, specifically the deck armour, although the offensive armament remained roughly the same. The design was superseded by the I3 and G3 battlecruiser designs, as both mounted a heavier main armament, and further improved the protection scheme, on roughly the same tonnage. The 1921 fleet program was cancelled due to signing of the Washington Naval Treaty in 1922, which limited the size and armament of battle