The armed forces of many nations have, at one time or another, used foreign volunteers who are motivated by political, ideological or other considerations to join a foreign army. These may be formed into units of a given nationality or may be formed into mixed nationality foreign units. Sometimes foreign volunteers were or are incorporated into ordinary units. The practice has a long history, dating back at least as far as the Roman Empire, which recruited non-citizens into Auxiliary units on the promise of them receiving Roman citizenship for themselves and their descendants at the end of their service.
Mixed nationality units Historic 60th (Royal American) Regiment of Foot. Composed of 'foreign Protestants'. Boer foreign volunteers Hohenlohe Regiment of France during the Bourbon Restoration. International Brigades of the Spanish Civil War The Islamic Legion of Libya under Muammar Qaddafi was composed of Muslim volunteers, primarily from the Sahel. Kempeitai Auxiliary units consisted of regional ethnic forces that were organized in areas occupied by the Japanese. King's African Rifles Papal Zouaves, a predominantly Catholic unit in service of the Papal States, resisting the Unification of Italy The SS (particularly the Waffen-SS) made extensive use of foreigners during World War II. For more information, see: Waffen-SS foreign volunteers and conscripts Rhodesian Light Infantry (initially all-Rhodesian, this unit became the "Foreign Legion" of the Rhodesian Army) Mahal – non-Israeli volunteers who fought for Israel in the 1948 Arab–Israeli War. There is to this day a voluntary program called Mahal in the Israeli army. Afghan mujahideen - many foreign Muslim volunteers joined the Afghan side of the Soviet invasion of Afghanistan. A few notable examples include Osama bin Laden (of Saudi Arabia), Abdullah Yusuf Azzam (Palestinian), Koshiro Tanaka (Japanese), and Ilyas Kashmiri (from Pakistani-administered Kashmir). The Maktab al-Khidamat was an international organisation founded by bin Laden and Azzam mobilise international support during the Afghan war, including by recruiting and training foreign mujahideen. Bosnian mujahideen were foreign Muslim volunteers who fought on the Bosniak side during the Bosnian War.
Current Also including nationals The Interbrigades of the Russo-Ukrainian War. Tercio de Extranjeros, or Tercio, or Spanish Legion - prior to 1987 and in the 2000s, after the abandonment of conscription, the Spanish Army is again accepting foreigners from select nationalities. The Legion today accepts male and female native Spanish speakers, mostly from Central American and South American states. Recruits are required to have a valid Spanish residence permit. Mujahideen Mujahideen in Chechnya - many foreign Muslim volunteers have also participated in the conflicts in the North Caucasus. See also: Islamic International Peacekeeping Brigade
Only including foreigners French Foreign Legion - Officer corps, predominantly French. International Freedom Battalion – An armed group of leftist foreign volunteers that fight in support of the Rojava Revolution in Syria. International Legion for the Defence of Ukraine – military unit formed to help defend the country from the 2022 Russian invasion. International Legion of the Defence Intelligence of Ukraine – special forces unit formed by the best foreign volunteers under command of the Main Directorate of Intelligence. Anti-Fascist Internationalist Front – An armed group of leftist foreign volunteers that fight in support of the People's Defensive War in Myanmar.
Units by nationality
American During both world wars, American volunteers served on the allied side before the US joined the war. During World War I, there were even a few Americans who volunteered to fly for the Imperial German Flying Corps. The Lafayette Escadrille in the French Air Force, World War I A number of American pilots flew with No. 32 Squadron RAF during World War I The 7th Air Escadrille (also known as the Kościuszko Squadron) in the Polish Air Force, Polish-Soviet War The Lincoln Brigade on the Republican side of the Spanish Civil War The Eagle Squadrons in the Royal Air Force, World War II The Flying Tigers in the Republic of China Air Force, World War II Before the US entered the war, many Americans joined the Canadian Forces, especially the RCAF, and served in ordinary Canadian units. The Five Yanks – Rachel Cox in Into the Dust and Fire records the history of five Ivy Leaguers (Chuck Bolte, Jack Brister, Bill Durkee, Heyward Cutting, and Robert Cox) who enlisted in the British Army and became the first Americans to fight the NazisWebcast Author Interview Rachel Cox Into the Fire 2012 The Crippled Eagles – American volunteers in Rhodesia (1965–1979)
Albanian The 21st Waffen Mountain Division of the SS Skanderbeg was a division of the German Waffen-SS that was developed around a nucleus of Albanian volunteers, named after Albanian medieval lord George Kastrioti Skanderbeg. It was better known for murdering, raping, and looting in predominantly Serb areas than for participating in combat operations on behalf of the German war effort.
Bangladeshi 8000 young men from Bangladesh volunteered to enlist in the PLO in 1987
Belgian Units from modern-day Belgium (then the Austrian Netherlands or United Kingdom of the Netherlands) served in the French armies of both the French Revolutionary and Napoleonic Wars During the Liberal Wars, a corps of Belgian volunteers fought for the Liberal side. The Belgian Legion during the Franco-Mexican War of 1864–1866 The 6 Février Battalion, part of the International Brigades during the Spanish Civil War was made up of French and Belgians. Their citizenship rights were revoked as a result of their decision to serve in a foreign army. Two Belgian units fought in the Waffen SS during the Second World War.
British During the Peninsular War, many Britons joined Spanish regular and irregular forces.Graciela Iglesias Rogers, British Liberators in the Age of Napoleon: Volunteering under the Spanish Flag in the Peninsular War (Bloomsbury Academic, London and New York, 2013) The state-sponsored Auxiliary Legion of the First Carlist War. The British Legions in the South American Wars of Independence during the 19th century. The British Free Corps of the Waffen SS in World War II. 2,500 British fought in the Spanish Civil War on the side of the republicans.Richard Baxell, Unlikely Warriors: The British in the Spanish Civil War and the Struggle Against Fascism (Aurum Press, London, 2012) In the Paraguay Revolution of 1922, British pilots fought in the Escuela de Aviación Militar. Many Britons fought during the American Civil War for both the United States and Confederate States. 67 British soldiers in the Union Army received the Medal of Honor. Dozens of British volunteers joined Croatian units and fought in the Yugoslav Wars between 1991 and 1995, most of them on the King Tomislav Brigade. Hundreds of British Nationals served in the Rhodesian Security Forces during the Rhodesian Bush War in the 1970s. A couple of dozen British volunteers joining several units of the Ukrainian military, particularly of the Ukrainian Foreign Legion, and the Azov Assault Brigade
Bulgarian Bulgarian Volunteer Corps. Fought for the Russian Empire during the Russo-Turkish War of 1877-1878.
Bosnian Bosnia and Herzegovina has seen some 300 people join the conflict in Syria and Iraq, making it one of the top per capita exporters of foreign fighters in Europe. The Bosnian War attracted large numbers of foreign fighters and mercenaries from various countries. Volunteers came to fight for a variety of reasons including religious or ethnic loyalties, but mostly for money. The 13th Waffen Mountain Division of the SS Handschar, composed mainly of Bosnian Muslims with some Catholic Croats, and mostly German officers The 23rd Waffen Mountain Division of the SS Kama, composed of German officers and Bosnian Muslim soldiers fought in World War II on the Axis' side
Canadian The 1st Canadian Regiment was a regiment of the Continental Army which fought during the American Revolutionary War. The 2nd Canadian Regiment was another regiment of the Continental Army which fought during the American Revolutionary War. During the American Civil War, between 33,000 and 55,000 men joined the Union Army with around another a few hundred joining the Confederate Army. Between February 1868 and September 1870 during the Risorgimento, 7 contingents of Canadian volunteers totaling 507 (most of whom were from Quebec) enrolled in the Papal army as part of the . The Mackenzie-Papineau Battalion (Mac-Paps) consisted of 1,500 Canadian volunteers who fought on the Republican side of the Spanish Civil War as part of the International Brigades. Often composed of working class Canadians and immigrants, the Mac-Paps were noted for being different from their comrades in the US Lincoln Brigade (often students and intellectuals). The Ilkka Machine Gun Company was a company sized unit that was attached to the Mackenzie-Papineau Battalion. It was composed of Finnish Canadians. 250 Canadians served in the Finnish American Legion during the Winter War. During the Vietnam War, between 20,000 and 40,000 Canadians volunteered in the United States Armed Forces to fight in Vietnam.Corday, Chris (10 November 2015). " Lost to History: The Canadians Who Fought in Vietnam". CBC News British Columbia. Retrieved 5 December 2017. The Canadian-Ukrainian Brigade is a unit of the Armed Forces of Ukraine that mainly consists of ex-Canadian servicemen.
Chinese The Chinese People's Volunteer Army that fought in the Korean War was nominally composed of volunteers sent by the People's Republic of China even though it was in fact composed of regular troops of the People's Liberation Army.
Croatian 20 to 30 Croatians fought as part of the far-right Azov volunteer battalion against Russian-backed rebels in eastern Ukraine since 2014 A total of 456 international volunteers from as many as 35 countries participated in the Croatian War of Independence (139 English, 69 French, 55 Germans, 33 Hungarians, 27 Dutch, 15 Australians) The 369th (Croatian) Reinforced Infantry Regiment as part of the German Wehrmacht, fought in World War II The 369th (Croatian) Infantry Division, as part of German Wehrmacht, fought in World War II The 373rd (Croatian) Infantry Division, as part of German Wehrmacht, fought in World War II The 392nd (Croatian) Infantry Division, as part of German Wehrmacht, fought in World War II The Croatian Air Force Legion, as part of the German Luftwaffe fought in World War II on the Axis' side The Croatian Anti-Aircraft Legion, as part of the German Luftwaffe fought in World War II on the Axis' side The Croatian Naval Legion, as part of the German the Kriegsmarine, fought in World War II on the Black Sea The Italian-Croatian Legion, unit of about 1,000 Croatian volunteers fighting for the Royal Italian Army Four Croatian Provisional Infantry Regiments of the French Imperial Army fought in the Napoleonic Wars. The Royal Cravat Cavalry Regiment of the French Royal Army founded in 1667 and disbanded in 1815
Czech The Czechoslovak Legion, which fought on various fronts of WW1, as well as the Russian Civil War. 1st Czechoslovak Army Corps in the Soviet Union.
Danish Danish-Baltic Auxiliary Corps, formed to defend Estonia against the Bolsheviks during the Russian Civil War.
Estonian In 1944, some 2,000 Estonians served in the Finnish Infantry Regiment 200 during the Continuation War.
Filipino The Spanish colonial army in the Philippines launched an expedition to Cambodia, which included Japanese mercenaries. Two hundred fifty French mercenaries served with British forces that invaded Manila in 1762. They changed sides and fought for the Spanish. In the 1770s, the Spanish colonial army in the Philippines had an Infantry Company of Cavite Malabars