The invention of mechs in the late 1950s spurred a revolution in ground warfare, as Oceanyka's otherwise inaccessible zones such as bogs and mountains, or covered terrain such as hills, were fit for war machines of this type. Mechs armed with weapons are named "gunmechs", and the most crude way to obtain one is to mount a light cannon on a bipedal chassis. Calibres such as 37mm, 40mm, 47mm or 50mm are the most common; the dominant cannon on crude gunmechs of this type is the British QF 2-pounder, due to its availability.