The stalemate of trench warfare in WWI was finally broken by the tank and self-propelled gun,and Germany capitulated. These weapons came fully into their own in WWII,and,combined with the tactics of Blitzkrieg,gave Germany early supremacy. Ground support aircraft such as the Stuka dive-bombers were used to devastating effect. The Soviet response to this combination was the T-34 tank whose 76 or 85mm gun could fire high explosive shells as well as armour-piercing rounds. The British response,the Matilda tank,was not heavily armoured but found its role when fitted with a flamethrower. Both Britain and the United States used stop-gap measures,fitting 25-pounder field guns onto tank chassis and hulls. Tank chassis were also equipped with revolving drums and minesweepers,with mortars and with bridge-laying hydraulic arms. After the war,the role of helicopters and aircraft in armoured assaults became essential. The US Army combined the use of these assault aircraft with the fire support of the M-109 self-propelled Howitzer,which is capable of firing nuclear shells over a distance of 15 miles. For saturation fire,NATO has developed the Multiple Launch Rocket System (MLRS),which in its 'smart' weapon form can penetrate the overhead armour of tanks using kinetic energy alone,and against which there is literally no defence.