Editing International Brigades (section)

=== Overview ===
{{for|military structure and organization|International Brigades order of battle}}
The first brigades were composed mostly of French, Belgian, Italian, and German volunteers, backed by a sizeable contingent of Polish miners from Northern France and Belgium. The [[XI International Brigade|XIth]], [[XII International Brigade|XIIth]] and [[XIII International Brigade|XIIIth]] were the first brigades formed. Later, the [[XIV International Brigade|XIVth]] and [[XV International Brigade|XVth]] Brigades were raised, mixing experienced soldiers with new volunteers. Smaller Brigades&nbsp;— the [[86th International Brigade|86th]], [[129th International Brigade|129th]] and [[150th International Brigade|150th]] – were formed in late 1937 and 1938, mostly for temporary tactical reasons.

About 32,000<ref name="Thomas 2003" /> foreigners volunteered to defend the Spanish Republic, the vast majority of them with the International Brigades. Many were veterans of World War I. Their early engagements in 1936 during the [[Siege of Madrid]] amply demonstrated their military and propaganda value.

The international volunteers were mainly socialists, communists, or others willing to accept communist authority, and a high proportion were [[Jewish volunteers in the Spanish Civil War|Jewish]]. Some were involved in the [[Barcelona]] [[May Days]] fighting against leftist opponents of the Communists: the Workers' Party of Marxist Unification ([[POUM]]) (''Partido Obrero de Unificación Marxista'', an anti-[[Stalinist]] Marxist party) and the [[anarchist]] [[CNT-FAI|CNT]] (CNT, Confederación Nacional del Trabajo) and [[Federación Anarquista Ibérica|FAI]] (FAI, Iberian Anarchist Federation), who had strong support in Catalonia. These libertarian groups attracted fewer foreign volunteers.

To simplify communication, the battalions usually concentrated on people of the same nationality or language group. The battalions were often (formally, at least) named after inspirational people or events. From spring 1937 onwards, many battalions contained one Spanish volunteer company of about 150 men.

Later in the war, military discipline tightened and learning Spanish became mandatory. By decree of 23 September 1937, the International Brigades formally became units of the [[Spanish Foreign Legion]].<ref name=" Beevor 2006/309">{{harvnb|Beevor|2006|p=309}}</ref> This made them subject to the Spanish Code of Military Justice. However, the Spanish Foreign Legion itself sided with the Nationalists throughout the coup and the civil war.<ref name=" Beevor 2006/309" /> The same decree also specified that non-Spanish officers in the Brigades should not exceed Spanish ones by more than 50 percent.<ref>{{harvnb|Castells |1974|pages= 258–259}}</ref> Also, the decree ruled that there must be a Spanish battalion in every international brigade, a Spanish company in every battalion, and a Spanish section in every company.<ref>Richard Baxell, ''The British Battalion of the International Brigades in the Spanish Civil War 1936-1939'' [PhD dissertation LSEPS], London 2001, p. 26. If applied rigorously, this order would reduce the number of foreigners in an international brigade to some 20%</ref>