For other meanings of stormtrooper see Stormtrooper (disambiguation).

The term Stormtrooper refers to special military troops which were formed in the last year of World War I as the German army developed new methods of attacking enemy trenches, called "infiltration tactics". Men trained in these methods were known as Sturmmann (Stormtroopers), formed into companies of Sturmtruppen (Storm Units). Other armies have used the term "assault troops", "shock troops" or fire teams for specialist soldiers who perform the infiltration tasks of stormtroopers.

With the withdrawal of Russia from World War I, the Germans were able to reinforce the Western Front with troops from the Eastern Front. This allowed them to take units out of the line and train in Hutier tactics (after Oskar von Hutier) to infiltrate and take trenches.

The methods developed to assault trenches during World War I before 1918 started with a lengthy artillery barrage all along the line followed by an assault from massed lines of infantry. Hutier suggested an alternate approach which consisted of these basic steps:

1. A short artillery bombardment, featuring heavy shells mixed with numerous poison gas projectiles would concentrate on neutralizing the enemy front lines, but not to destroy them.
2. Under a creeping barrage, German shock troops (Sturmbatallione) would move forward and infiltrate the Allied defenses at previously identified weak points. They would avoid combat whenever possible and attempt to destroy or capture enemy headquarters and artillery strongpoints.
3. After the shock troops had done their job, German Army units, heavily equipped with machine guns, mortars and flamethrowers, would make heavy attacks along narrow fronts against any Allied strongpoints the shock troops missed. When the artillery was in place, officers could direct the fire wherever it was needed to accelerate the breakthrough.
4. In the last stage of the assault, regular infantry would mop up any remaining Allied resistance.

The new assault methods involved men rushing forwards in small groups using whatever cover was available and laying down covering fire for other groups in the same unit as they moved forwards. The new tactics, which were intended to achieve tactical surprise, were to attack the weakest parts of an enemy's line, bypass his strongpoints and to abandon the futile attempt to have a grand and detailed plan of operations controlled from afar. Instead, junior leaders could exercise initiative on the spot. Any enemy strong points which had not been over-run by stormtroopers could be attacked by second echelon troops following the stormtroopers.

On March 21, 1918 Germany launched a major offensive, "Operation Michael", against British and Commonwealth forces, using the new methods and tactics. Four successive German offensives followed, that of May 27 and for the first time in 4 years the stalemate of trench warfare was broken.