The Umbaran mobile heavy cannon (UMHC) was a model of walker used by Umbarans during the Clone Wars. Later, both the Imperial Army and Alliance to Restore the Republic used them during the Galactic Civil War, with the Alliance operating stolen Imperial machines and providing them to Saponza's Gang.
MHCs were heavily armored, impervious to blasters and even missile launchers, and had an articulated electromagnetic plasma cannon mounted on top of its dome-like body. The Imperial Military used a remodeled variant known as the Cold-weather Mobile Heavy Cannon. This prototype model was specialized in sub-zero temperatures.
During the Battle of Umbara, MHCs attacked Captain Rex and the 501st Legion as they advanced down a narrow gorge as part of an ill-advised strategy by Jedi General Pong Krell. The clone troopers lacked the firepower to destroy the MHCs, and as they began to suffer heavy casualties, Rex sent "Fives" and "Hardcase" to steal the Umbaran's own weaponry to try to destroy the enemy armor. The two clones managed to steal Umbaran starfighters from the nearby Umbaran airbase and used them to destroy the MHCs.