Mortar

choi

The 60mm Wonder Got Better. Strategy Page, May 26, 2012
http://strategypage.com/htmw/htweap/articles/20120526.aspx
("Infantry mortars were invented during World War I (1914-18), but have been largely unchanged since then")

My comment:
(a) There is no need to read the rest.
(b) mortar (weapon)
http://en.wikipedia.org/wiki/Mortar_(weapon)
(typically muzzle-loading; section 3 History: it was not until the Stokes trench mortar devised by Sir Wilfred Stokes [1860-1927; English] in 1915, that the modern mortar transportable by one person was born)

* cannon
http://en.wikipedia.org/wiki/Cannon
("In the modern era, the term cannon has fallen out of common usage, replaced by "guns" or "artillery" if not a more specific term such as "mortar" or "howitzer". In aviation, cannon remains a common term for aircraft guns"; First used in China)