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.
- 1 Mixed nationality units
- 2 Units by nationality
- 2.1 American
- 2.2 Belgian
- 2.3 British
- 2.4 Chinese
- 2.5 Croatian
- 2.6 Filipino
- 2.7 French
- 2.8 German
- 2.9 Greek
- 2.10 India
- 2.11 Irish
- 2.12 Israel
- 2.13 Italian
- 2.14 Nepalese
- 2.15 Moroccan
- 2.16 Polish
- 2.17 Portuguese
- 2.18 Rhodesian
- 2.19 Russian
- 2.20 Serbian
- 2.21 Scottish
- 2.22 South African
- 2.23 Spanish
- 2.24 Swedish
- 2.25 Swiss
- 2.26 Taiwanese
- 2.27 Ukraine
- 3 See also
- 4 References
Mixed nationality units
- 62nd (Royal American) Regiment of Foot. Composed of 'foreign Protestants'.
- French Foreign Legion
- Hohenlohe Regiment of France during the Bourbon Restoration.
- International Brigades of the Spanish Civil War
- Islamic Legion
- King's African Rifles
- Mahal – non-Israeli volunteers who fought for Israel in the 1948 Arab–Israeli War. There is to this day a Mahal program in the Israeli army.
- 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
- 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.
- Rhodesian Light Infantry (initially all-Rhodesian, this unit became the "Foreign Legion" of the Rhodesian Army)
- The United States Military has a long tradition of foreign volunteers taking up arms for the United States. Foreign born officers, such as the Marquis de Lafayette, Tadeusz Kościuszko, and Friedrich Wilhelm von Steuben provided vital contributions to the cause of independence. During the nineteenth century the US Army made extensive use of foreign soldiers, particularly Irish and German. German Jewish troops were common during World War II. Presently, many members of the US Marine Corps are of Latin American and not US nationality. However, many if not most non-American troops in the United States armed forces are usually seeking the expedited United States citizenship that comes with completion of a term of service, and can be seen as aspiring Americans rather than outright foreigners.
- International Freedom Battalion – An armed group of leftist foreign volunteers that fight in support of the Rojava Revolution in Syria.
Units by nationality
During both world wars, American volunteers served on the allied side before the USA 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
- 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 Chinese 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.
- A number of American pilots flew with No. 32 Squadron RAF during World War I
- 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 Nazis
- The Crippled Eagles
- 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
- The Belgian Legion during the Franco-Mexican War of 1864-6
- 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
- During the Peninsular War, many Britons joined Spanish regular and irregular forces.
- 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.
- 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.
- 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.
- The 13th Waffen Mountain Division of the SS Handschar, fought in World War II on the Axis' side
- The 23rd Waffen Mountain Division of the SS Kama, fought in World War II on the Axis' side
- The 369th (Croatian) Reinforced Infantry Regiment as part of 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 I
- The Croatian Air Force Legion, as part of German Luftwaffe fought in World War II on the Axis' side
- The Croatian Naval Legion, as part of the German Kriegsmarine, fought in World War II on the Black Sea
- The 1st Yugoslav Volunteer Brigade, fought in World War II under Red Army command. Later became part of the Yugoslav Army.
- About five thousand Filipinos served in a militia called the Makapili, which was under Japanese command. The unit was formed on 10 November 1944 and was issued around two thousand rifles by the Japanese. Its headquarters was located at the Christ the King compound in Quezon City. The organization was active in the Manila area, and in the nearby provinces of Rizal, Laguna, Bulacan, and Nueva Ecija. This militia made its last stand at Marikina in 1945.
- French Foreign Legion accepts foreigners
- 9,000 French fought in the International Brigades during the Spanish Civil War in the side of the Republicans.
- Some French emigres who fled to Britain fought in the British Army of the Napoleonic Wars
- Charlemagne Regiment of the SS fought for Germany in the Second World War
- Chasseurs Britanniques of the Napoleonic Wars
- Legion of French Volunteers Against Bolshevism a collaborationist force of French who fought Soviet partisans for Nazi Germany
- From 1991 to 1994, during the Croatian War of Independence and the Bosnian War, a number of French volunteers fought along the Croats in the King Tomislav Brigade.
- 7 Independent Company (Rhodesia)
- King's German Legion in the Napoleonic Wars
- In the Spanish Civil War, the state-sponsored Condor Legion fought for the Nationalists, while the Thaelmann Battalion fought for the Republicans.
- During the American Civil War Germany was the place of birth for thousands of Union soldiers. Several German speaking regiments existed such as the 9th Ohio Infantry, or the 74th Pennsylvania Infantry.
- From 1991 to 1994, during the Croatian War of Independence and the Bosnian War, a number of former Bundeswehr and East-German army members fought along the Croats in the King Tomislav Brigade. The brigade's executive officer at the time of the outbreak of the Bosnian Croat War was former Bundeswehr officer Jürgen Schmidt, who died while leading his troops against Bosnian Muslim forces near Gornji Vakuf, in January 1993. In another action, a German-volunteer patrol, led by former Bundeswehr member Michael Homeister, ambushed and killed two Serbs manning an observation post.
- The Free Indian Legion was a volunteer legion made up of Indian POWs. The legion was first part of the Wehrmacht but transferred to the Waffen-SS late in the war.
See Also Irish Military Diaspora
- The Irish Brigade in the French Army from 1690 and through the eighteenth century.
- The Irish Legion fought for Imperial France during the Napoleonic Wars
- 1st Regiment Venezuelan Rifles – Irish regiment that was part of the British Legions fighting in the South American Wars of Independence took part in the Venezuelan War of Independence.
- St. Patrick's Battalion in the Mexican Army during the Mexican–American War.
- The Irish Brigade which served on the Union side in the American Civil War in the 1860s
- Irish commandos in the Boer Army during the Boer War
- Connolly Column, fought for the Spanish republic in the Spanish civil war
- The Irish Brigade which fought for the Nationalist rebels in the Spanish Civil War
- Mahal – Program for non-Israelis between the age of 18–24 to serve in the IDF.
- The Redshirts of Giuseppe Garibaldi fought in Southern Italy and Uruguay.
- Corpo Truppe Volontarie in the Spanish Civil War.
- Division Garibaldi fought under Josip Broz Tito's command as a part of NOVJ in Dalmatia and Bosnia, during the Second World War 
- Gurkhas in the British Army.
- Gorkhas in the Indian Army.
- Gurkha Contingent in the Singapore Police Force
- Gurkha Reserve Unit – a similar type force in Brunei
- Brigades in the Spanish Civil War.
- Polish Lancers and other Polish forces in the Army of Napoleon.
- Polish Volunteers in many wars and revolutions of the 19th century, including Spring of Nations, Crimean War (on Turkish side) and The Paris Commune.
- The Blue Army, fought on the French side in WW1.
- The Rhodesian Army accepted foreign volunteers, almost all of whom were required to speak English, as they were integrated into regular units (usually the Rhodesian Light Infantry) alongside locally based soldiers. The exception was 7 Independent Company, a short-lived unit made up entirely of French-speaking personnel, led by francophone officers, which existed between 1977 and 1978.
- The Armed Forces of the Russian Federation have since 2010 or so begun to recruit CIS volunteers. See Armed Forces of the Russian Federation#Personnel.
- The Serb Volunteer Guard, Fought in the Croatian War of Independence and the Bosnian War supporting the Serb forces like the Army of Republika Srpska.
- Yugoslav brigadistas (Spanish: brigadistas yugoslavos), a contingent from the Kingdom of Yugoslavia who fought beside the Republican side (In support of the Second Spanish Republic).
- The Serbian Volunteer Corps was an Axis collaborationist group during WWII that helped fight against partisan forces in Serbia.
- Scots have a long history of service in the armies of Kings of France since at least the ninth century. The Scottish Guard was formally created by the French King Charles VII in 1422, and existed until the end of the Bourbon Restoration period in 1830.
- The Blue Division of World War II fighting with Germany against the USSR.
- The Blue Legion was formed late in the Second World War out of Blue Division soldiers who refused to leave after Franco required all Spaniards to leave Axis forces.
- The 9th Armoured Company of the Free French Forces.
- The Spanish Legion accepts foreign recruits.
- Swedish Voluntary Air Force fighting for the Finnish side in the Winter War
- Swedish Volunteer Corps fighting for the Finnish side in the Winter War
- Hundreds of Swedes volunteered in the 5th SS Panzer Division Wiking to fight against the USSR.
- Takasago Volunteers were volunteer soldiers in the Imperial Japanese Army recruited from the Taiwanese aboriginal tribes during World War II.
- The 14th Waffen Grenadier Division of the SS (1st Galician) was made up nearly entirely of ethnic Ukrainians.
- The Ukrainian Liberation Army was a division of the Wehrmacht that fought all over Europe.
- The Nachtigall Battalion was a battalion of the Wehrmacht made up of Ukrainian nationalists who fought against the USSR.
- The Roland Battalion was a battalion of the Wehrmacht made up of Ukrainian nationalists who fought against the USSR.
- The Roland and Nachtigall battalions were later reorganized into the 201st Schutzmannschaft.
- The Ukrainian National Army fought against the USSR in the last days of WWII.
- Thousands of Hiwis were of Ukrainian origin.
- List of militaries that recruit foreigners
- Europäische Freiwillige of the Second World War
- Foreign legions
- Military volunteer
- Spanish Civil War and Foreign Involvement
- Foreign support in the Winter War
- White Tights, alleged Baltic female snipers in Chechnya
- Webster, Graham (1979). The Roman Imperial Army (Second ed.). London: A & C Black. p. 144. ISBN 0-7136-1909-0.
- Herris, Jack (2010). Aircraft of World War I, 1914-1918 (2017 reprint ed.). London: Amber Books Ltd. p. 55. ISBN 978-1-906626-65-5.
- Webcast Author Interview Rachel Cox Into the Fire 2012 ISBN 9780451234759
- 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) ISBN 978-1-4411-3565-0
- Richard Baxell, Unlikely Warriors: The British in the Spanish Civil War and the Struggle Against Fascism (Aurum Press, London, 2012)
- Arielli, Nir. "In Search of Meaning: ForeignVolunteers in the Croatian Armed Forces, 1991–95". Academia.edu. Missing or empty
- Krott, Rob (2008). Save the Last Bullet for Yourself: A Soldier of Fortune in the Balkans and Somalia. Casemate. pp. 168–69. ISBN 978-1935149712.
- Krott (2008, p. 148)
- "Venezuela's Irish Legacy Copyright 1991 by Brian McGinn".
- "Garibaldi Division". Vojska.net. Retrieved 2013-09-17.