In warfare, infiltration tactics involve small, lightly equipped infantry forces attacking enemy rear areas while bypassing enemy front line strongpoints and isolating them for attack by follow-up troops with heavier weapons.
Development during World War I 
These tactics emerged gradually during the later years of World War I, used in various forms by the Russian general Aleksei Brusilov in the Brusilov Offensive of 1916, by the British Third Army at the Battle of Arras in April 1917, following the reorganisation of British infantry platoons according to the new Manual SS 143, in the new year and by the Germany military in the Siege of Riga in September 1917 and the Battle of Caporetto in October 1917.
The tactics became especially associated with the stormtroopers of the German Army, and were also called Hutier tactics, after General Oskar von Hutier, who used these tactics to great effect during Operation Michael in March 1918.
Infiltration tactics were first supposedly proposed in the Allied armies by French Army captain Andre Laffargue., though there is some dispute over whether the methods Laffargue proposed can properly be classified as infiltration tactics. Laffargue published a pamphlet "The attack in trench warfare" in 1915, based upon his experiences in combat that same year. He advocated that the first wave of an attack identify hard-to-defeat defenses but not attack them; subsequent waves would do this.
The French published his pamphlet "for information", but did not implement it. The British did not even translate it, but did gradually adopt the techniques, beginning with the Canadian Corps. Germany captured copies of the pamphlet in 1916, translating and issuing it to units, but already had more sophisticated infiltration tactics: an experimental Pioneer unit commanded by Hauptmann Willie Rohr had been formed in the spring of 1915, over two months before Laffargue's pamphlet was published.
Hutier tactics 
Named for the German general of the infantry Oskar von Hutier. Infiltration attacks began with brief and violent bombardments of the enemy front lines, to suppress and demoralize the soldiers stationed there. The bombardment also targeted the enemy rear areas to destroy or disrupt roads, artillery, and command units.
This was done to confuse the enemy, and reduce their capability to launch effective counterattacks from secondary defense lines. For maximum effect, the exact points of attack remained concealed until the last possible moment.
Light infantry led these attacks. They would attempt to penetrate enemy weak points to bypass and isolate heavily defended positions in the front line. Infantrymen with heavier weapons would then follow-up and have a great advantage when attacking the isolated enemy strong points. Other reinforcements would then enter these breaches, and the entire enemy line would shortly collapse. The attacks relied heavily on speed and surprise.
This tactic initially worked well and saw heavy use. However, because of this extensive implementation, the enemy quickly developed effective defenses. Also, as in the case of the more traditional mass attack, reserve troops following the assault units had to consolidate any gains against an enemy counterattack.
One of the problems of World War I was that even when a breakthrough was made, the ground was so devastated that moving up reserves and material was difficult, allowing the enemy time to regroup. Thus, even with the new tactics and their relatively light use of artillery, attacks would tend to bog down sooner or later, and no massive breakthrough was possible.
Dien Bien Phu 
At the Battle of Dien Bien Phu, Major Marcel Bigeard, commander of the French 6th Colonial Parachute Battalion (6th BPC), used infiltration tactics in an attempt to defend the besieged garrison against the Viet Minh trench warfare tactics. Bigeard's parachute assault companies were supported by concentrated artillery and air support, and received help from tanks, allowing two companies (1st under Lieutenant René Le Page and 2nd under Lieutenant Hervé Trapp) numbering no more than 180 men to recapture the important hilltop position of Eliane 1 from a full Viet Minh battalion, on the early morning of 10 April 1954.
Other parachute battalion and company commanders also used similar tactics during the battle.
- CSI Report No. 13: Tactical responses to concentrated artillery: Introduction (Combat Studies Institute, U.S. Army Command and General Staff College, Fort Leavenworth).
- Gudmundsson, Stormtroop Tactics
- CSI Report No. 13: Tactical responses to concentrated artillery: Ch 2 (Combat Studies Institute, U.S. Army Command and General Staff College, Fort Leavenworth).
- Samuels, Martin Doctrine and Dogma, passim
- Samuels, Martin Command or Control?, passim
- Stormtroop Tactics, Appendix C and passim
- Samuels, Martin Doctrine and Dogma, 55
- Davidson, Vietnam at War, page 265.
- Davidson, Phillip B. Vietnam at War: The History, 1946–1975. New York: Oxford University Press, 1991. ISBN 0-19-506792-4, ISBN 0-89141-306-5.
- Gudmundsson, Bruce I. Stormtroop Tactics: Innovation in the German Army, 1914–1918. New York: Praeger, 1989. ISBN 0-275-93328-8.
- Samuels, Martin. Doctrine and dogma: German and British infantry tactics in the First World War. New York: Greenwood Press, 1992. ISBN 0-313-27959-4.
- Samuels, Martin. Command or control?: Command, training, and tactics in the British and German armies, 1888–1918. London; Portland, Oregon: Frank Cass, 1995. ISBN 0-7146-4570-2, ISBN 0-7146-4214-2.
Further reading 
- House, Jonathan M. Toward Combined Arms Warfare: A Survey of 20th-Century Tactics, Doctrine, and Organization. U.S. Army Command General Staff College, 1984. Available online (5 February 2005) or through University Press of the Pacific (Honolulu, Hawaii, 2002). ISBN 1-4102-0159-7.
- Pope, Stephen, Elizabeth-Anne Wheal, and Keith Robbins, eds. The Macmillan Dictionary of the First World War. London: Macmillan Reference Books, 1995. ISBN 0-333-61822-X.