A howitzer is a type of artillery piece characterized by a relatively short barrel (barrel length 15 to 25 times the caliber of the gun) and the use of comparatively small propellant charges to propel projectiles at relatively high trajectories, with a steep angle of descent. In the taxonomies of artillery pieces used by European (and European-style) armies in the eighteenth, nineteenth, and twentieth centuries, the howitzer stood between the ""gun"" (characterized by a longer barrel, larger propelling charges, smaller shells, higher velocities, and flatter trajectories) and the ""mortar"" (which could fire at even higher angles of ascent and descent). Howitzers, like other artillery pieces, are usually organized in groups called batteries.