Some special forces operations, such as counter-terrorism actions, may be carried out domestically under certain circumstances. Special forces units are typically composed of relatively small groups of highly-trained personnel equipped with specialist equipment and armament, operating under principles of self-sufficiency, stealth, speed, and close teamwork, often transported by helicopter, small boats or submarines, parachuting from aircraft, or stealthy infiltration by land. Special forces are sometimes considered a force multiplier, as when they train indigenous forces to fight guerrilla warfare.
In antiquity, Hamilcar Barca in Sicily had specialized troops trained to launch several offensives per day. Later, during the Crusade wars, small, highly trained units of Knights Templar attacked individual Muslim units attempting to forage or seize booty. Muslim armies had several naval special operations units, including one which used camouflaged ships to gather intelligence and launch raids, and another which consisted of soldiers who could pass for Crusaders who would use ruses to board enemy ships and then capture and destroy them. In ancient China and Feudal Japan, specially trained martial artists, called Ninja, were employed to fight guerilla warfare, unconventional warfare, as well as engage in espionage and assassinations.
During the Napoleonic wars, rifle and sapper units existed who were not committed to the formal lines that made up most battles of the day. They instead held more specialised roles in reconnaissance and skirmishing.
For the British Army, it was during the Second Boer War (1899-1902) that the need for more specialised units became most apparent. Scouting units such as Lovat Scouts, a Scottish Highland regiment made up of phenomenal woodsmen outfitted in ghillie suits and well practiced in the arts of marksmanship, field craft, and military tactics, best filled this role. This unit was formed in 1900 by Lord Lovat and early on reported to an American, Major Frederick Russell Burnham, the Chief of Scouts under Lord Roberts. After the war, Lovat's Scouts went on to formally become the British Army's first sniper unit. Additionally, the formation of the Bushveldt Carbineers in 1901 may also be seen as an early manifestation of a unit for unconventional warfare.
During World War II in 1940 the British Commandos were formed following Winston Churchill's call for "specially trained troops of the hunter class, who can develop a reign of terror down the enemy coast." The Commandos were selected from volunteers among existing servicemen and went on to spawn a number of other specialist units including the Long Range Desert Group, the Special Air Service, the Special Boat Service and the Small Scale Raiding Force of the Special Operations Executive.
In the Burma Campaign, the Chindits, whose long range penetration groups were trained to operate from bases deep behind Japanese lines, contained commandos (King's Regiment (Liverpool), 142 Commando Company) and Gurkhas. Their jungle expertise, which would play an important part in many British special forces operations post war, was learnt, at a great cost in lives, in the jungles of Burma fighting the Japanese.
In mid-1942, the United States formed the Rangers. The United States and Canada also formed a sabotage ski brigade for operations in Norway who became known as the Devil's Brigade during their eventual service in Italy. Merrill's Marauders were modelled on the Chindits and took part in similar operations in Burma.The foundation date of No 2 Dutch Troop, 22 March 1942, is considered to be the foundation date of the Korps Commandotroepen )Dutch special forces)
In late November 1943, the Alamo Scouts were formed to conduct reconnaissance and raider work in the Southwest Pacific Theater under the personal command of then Lt. General Walter Krueger, Commanding General, Sixth U.S. Army. Krueger envisioned that the Alamo Scouts, consisting of small teams of highly trained volunteers, would operate deep behind enemy lines to provide intelligence-gathering and tactical reconnaissance in advance of Sixth U.S. Army landing operations. In 1988, the Alamo Scouts were individually awarded the SPECIAL FORCES SHOULDER TAB for their services in World War II and included in the lineage of today's U.S. Army Special Forces.
The German army had the Brandenburger Regiment, which was originally founded as a special forces unit used by the Abwehr for infiltration and long distance reconnaissance in Fall Weiss of 1939 and the Fall Gelb and Barbarossa campaigns of 1940 and 1941. Later during the war the SS- Jagdverbände, a unit within the Waffen SS commanded by Otto Skorzeny, also conducted many special operations.
On October 21, 1944 Adolf Hitler — inspired by an American subterfuge which had put three captured German tanks flying German colours to devastating use at Aachen — summoned Skorzeny to Berlin and assigned him to lead a panzer brigade. As planned by Skorzeny in Operation Greif, about two dozen German soldiers, most of them in captured American army Jeeps and disguised as American Military Police officers, penetrated American lines in the early hours of the Battle of the Bulge and sowed disorder behind the Allied lines by mis-directing convoys away from the front lines. A handful of his men were captured by the Americans and spread a rumour that Skorzeny was leading a raid on Paris to kill or capture General Eisenhower. Although this was untrue, Eisenhower was confined to his headquarters for weeks and Skorzeny was labelled "the most dangerous man in Europe".
In Italy, the Decima Flottiglia MAS were responsible for the sinking and damage of considerable Allied tonnage in the Mediterranean. After the division of Italy in 1943, those fighting with Germany retained the original name and those fighting with the Allies retitled as the Mariassalto.
In Finland, Long Range Reconnaissance Patrols (Kaukopartio) were used extensively to perform reconnaissance missions deep behind Soviet lines. Occasionally they were also used to destroy strategic targets.
Throughout the later half of the 20th century and into the 21st century, special forces have come to higher prominence, as governments have found objectives can sometimes be better achieved by a small team of anonymous specialists than a larger and much more politically controversial conventional deployment. In both Kosovo and Afghanistan, special forces were used to co-ordinate activities between local guerrilla fighters and air power. Typically, guerrilla fighters would engage enemy soldiers and tanks causing them to move, where they could be seen and attacked from the air.
The US led invasion of Afghanistan involved coalition special forces from several nations, who played a major role in removing the Taliban from power in 2001-2002. Coalition special forces have continued to play a role in combating the Taliban in subsequent operations. Special forces involved in these operations, occasionally working together, included US Special Operations Forces, UK Special Forces, the Australian Special Air Service Regiment, the Canadian Joint Task Force 2, the German KSK, the New Zealand Special Air Service and the Norwegian Forsvarets Spesialkommando and Marinejegerkommandoen. Special forces from other nations have supported the parallel NATO mission in Afghanistan.
Invariably, special forces were used in military operations such as the Vietnam War, Falklands War, The Troubles in Northern Ireland, the first and second Gulf Wars, Afghanistan, Kosovo, Bosnia, first Chechen War and second Chechen War, the Iranian Embassy siege (London), Operation Defensive Shield, Moscow theater hostage crisis, Japanese Embassy hostage crisis (Lima) and in Sri Lanka against the LTTE.