At the dawn of World War II, the 90mm gun replaced the aging 3-inch gun as the staple of Army heavy antiaircraft artillery and became one of the finest artillery pieces fielded by the Allies. Developed beginning in earnest in 1938 to counter faster, higher-flying aircraft, the 90mm gun M1 was standardized in March 1940, followed by the M1A1 version with a small loading tray and accommodations for a spring rammer to speed reloading. The improved M2 gun, standardized in May 1943, had a redesigned breech with a fully automatic fuze setter-rammer that raised the rate of fire to 23 to 28 rounds per minute. Its mounts also evolved, from the original M1 spider design with a detachable platform and single-axle dual-wheeled bogie, to the M1A1 mount with remote control through electric-hydraulic mechanisms, and then to the enhanced M2 mount intended to improve performance against ground targets. The M2 mount added front and rear two-tire bogies, folding platforms, armor shielding for the crew, the ability to fire without full emplacement, and depression to -10°, allowing quicker engagement of air and ground targets, including troops, armored vehicles, and water craft. Early test versions of the M2 mount reached the field with M1 or M1A1 guns before the M2 gun's rammer was completed. A fixed-mount M3 pedestal for the M1 gun was also heavily armored and designed mainly for use against motor torpedo boats, though it could also elevate to +80° and engage aircraft by manual or remote control. All 90mm mounts included a direct fire sighting system for ground targets or watercraft.