The SS were Hitler's shock troops.
The United States Marine Corps is used as shock troops.
During World War II the Red Army of the Soviet Union deployed five Shock armies. Many of the units which spearheaded the Soviet offensives on the Eastern Front from the Battle of Stalingrad to the Battle of Berlin were Shock Armies. Shock Armies had high proportions of infantry, engineers and field artillery, but with less emphasis on operational mobility and sustainability. Soviet Shock Armies were characterized by a higher allocation of army-level artillery units to break German defense positions by weight of fire, and often had heavy tank regiments or heavy self-propelled gun regiments to add additional direct fire support. Once a breach in the enemy tactical position was made, more mobile units such as tank and mechanized corps would be inserted through the Shock Army's positions with the mission of penetrating deep into the enemy rear area. By the end of the war, though, Soviet Guards Armies typically enjoyed superior artillery support to that of the shock armies.
Well-known Shock Armies include the 2nd Shock Army, which spearheaded several offensives in the Leningrad area, and the 3rd Shock Army, which played a key role in the Battle of Berlin.
A Soviet ad hoc combat group was a mixed arms unit of about eighty men in assault groups of six to eight men, closely supported by field artillery. These were tactical units which were able to apply the tactics of house to house fighting that the Soviets had been forced to develop and refine at each Festungsstadt (fortress city) they had encountered from Stalingrad to Berlin.