A great historic video of the US Military mortar that is considered the largest and most powerful mortar that has ever been built. Little David was the nickname of an American 36 inches (910 mm) caliber mortar used for test firing aerial bombs during World War II, that is one of the largest calibre guns ever built, having a larger calibre than both of Germany’s Dora and Gustav which were 31.5 inches (800 mm) railway guns. Great Britain’s Mallet’s Mortar had an identical calibre.
image/text credit: ArmedForcesUpdate
The mortar was originally used as the launching mechanism for test-firing aerial bombs at Aberdeen Proving Ground (during the war, bombs became larger and larger necessitating the construction of such a large calibre gun). Little David was therefore not intended as a combat weapon. The mortar’s base was a large steel box. The base was placed below ground, with its top flush with the surrounding surface, allowing the mortar’s muzzle to be lowered horizontal for loading at ground level.
By 1944, it was expected that the US forces would encounter extremely strong fortifications during the expected invasion of Japan. Studies began on using Little David as a siege mortar. The mortar was converted into a two piece mobile unit, consisting of the 80,000 pounds (36,000 kg) barrel and the 93,000 pounds (42,000 kg) base transported by two artillery tractors.
In addition to the two main loads, the Little David unit would also include a bulldozer and crane with bucket to dig the emplacement for the mortar’s base.The huge mortar could be ready to fire in 12 hours. The largest (800 mm) known German artillery weapons were hauled on 25 railway cars and required three weeks to put in firing position.