Engelmann Joachim. German heavy mortars

Pennsylvania, USA: Schiffer Publishing Ltd. 1991 – 52 p.
ISBN: 0-88740-322-0Mortars are considered to be one of the earliest forms of artillery weapons. They began life as siege weapons, breaking down the walls and ramparts of fortified positions, and later also became used in the opposite role as fortress guns. Since the 13th/14th century, the mortar's primary characteristics have been a steep angle of fire coupled with increased penetrating power, a large caliber (up to
80cm) using heavier projectiles, and a relatively short range. For all this, however, mortars are usually stationary weapons or, when mobile, extremely cumbersome.
The name "mortar" basically means a "sturdy container made of metal with a semi-spherical bottom chamber", or later, a chamber which "directs the explosive force in a predetermined direction and propels projectiles."