While her 12-inch belt armour was considered sufficient against most capital ships she was likely to encounter, her 3 inches of deck armour left her vulnerable to plunging fire at long range. At the time of her commissioning in World War I, naval gunnery was severely inaccurate at the ranges necessary to produce plunging fire, and "Hood's" greater speed and maneuverability were seen as an acceptable trade-off. However, as the accuracy of naval gunfire increased in the inter-war period, "Hood" was eventually scheduled to receive an upgrade in 1939 that would have doubled her deck armour to 6 inches, but the outbreak of World War II meant the upgrade never took place. She thus sortied to war at a marked disadvantage against the new capital ships of the Axis.