The Stormtroopers (in German Stoßtruppen, "shock troops") were specialist military troops which were formed in the last years 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 in Germany as Sturmmann (literally "assault man" but usually translated as Stormtrooper), formed into companies of Sturmtruppen ("assault troops", more often and less exactly Storm Troops). The infiltration tactics developed by the stormtroopers are still in use today, in one form or another. Other armies have also used the term "assault troops", "shock troops" or fireteams for specialist soldiers who perform the infiltration tasks of stormtroopers.
The concept of "Stormtroopers" developed from its beginning in March 1915, when a unit known as Sturmabteilung Calsow (Calsow's Assault Detachment) under Major Calsow was formed by the Eighth Army, by orders from the War Ministry, consisting of headquarters, two pioneer companies and a 37mm gun (Sturmkanone) battery. The unit was to use heavy shields and body armor as protection in attacks.
This unit was however never employed in its intended role, instead used to defend against attacks in France. In June, this improper use of the unit had already cost the unit half its manpower, and for this, Major Calsow was relieved, against his protests that it was not his fault that the unit was not used as intended.
The new commander of the Assault Detachment from 8 September 1915 was a Hauptmann Rohr, previously commander of the Guard Rifle Battalion. The detachment was reinforced with a machine gun platoon, and a flamethrower platoon. The old infantry support guns had been shown to be too difficult to move across the battlefield, and a new model was developed based on captured Russian 76.2mm fortress guns and issued to the Assault Detachment.
Captain Rohr at first experimented with using the body armor and shields already in the Detachment's inventory, but realized that speed was better protection than armor. The only piece of armor kept was the stahlhelm, a new model of steel helmet that later became the standard in all German units at the end of World War I, and throughout the Second World War.
The new tactics developed by Captain Rohr, building much on his own previous experiences from the front, was based on the use of squad sized stormtroops ("Sturmtruppen" or "Stoßtruppen"), supported by a number of heavy support weapons and field artillery that was to be coordinated at the lowest level possible, and rolling up enemy trenches using troops armed with hand grenades. These tactics were tested the first time in October 1915 in a successful assault on a French position in the Vosges Mountains.
In December 1915, the Assault Detachment started giving courses to officers and soldiers of other German units, training them in the new assault tactics. Around this time the unit also changed some of its equipment to better fit its new requirements. Lighter footwear was issued, and uniforms reinforced with leather patches on knees and elbows to protect them when crawling. Special bags designed to carry grenades replaced the old belts and ammunition pouches, and the standard Gewehr 98 rifle was replaced with the lighter Karabiner 98a previously used by cavalrymen. While continuing to educate other units, the Detachment also participated in many small trench raids and attacks with limited objectives.
The first major offensive led by the new Assault Detachment was during the first days of the Battle of Verdun in February 1916. Stormtroops from the Assault Detachment was used in the first wave leading some units into the French trenches, attacking seconds after the barrage had lifted. This generally worked very well, even though it worked much better against the first trenchline than against the less well-known enemy rear-area.
On 1 April 1916, the Assault Detachment was redesignated "Assault Battalion Rohr". Around this time it also increased its size from two to four pioneer companies. At the same time, work began on transforming several Jäger battalions into new Assault Battalions.
At a larger scale, the storm tactics was first used by the Russians in June 1916 during the Brusilov Offensive with great success. But, due to the February Revolution in Russia, no further development of the tactics was carried out on the Russian side. 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.
In February 1917, the British Army manual SS 143 advocated more sophisticated infiltration tactics than the Germans created. Using them throughout 1917 the British perfected all-arms battle. The British used rifles, rather than grenades as they were more effective. They were also supported by sophisticated sound-ranging, something the German Army never perfected.
On 21 March 1918, Germany launched a major offensive, "Operation Michael", against Allied forces, using the new methods and tactics. Four successive German offensives followed, that of 27 May and for the first time in four years the stalemate of trench warfare was broken. However, poor posture inflicted heavy casualties on attacking troops. German units often moved around in tightly-packed clouds and suffered appalling losses. The German advance had stalled by July and the Allies began their Hundred Days Offensive..
The methods developed to assault trenches during World War I before 1918 usually 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, combining some previous and some new attacks in a complex strategy:
The new assault methods involved men rushing forward in small groups using whatever cover was available and laying down suppressive fire for other groups in the same unit as they moved forward. 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.