Mixed brigade () was a basic tactical military unit of the Republican army during the Spanish Civil War. It was initially designed as "pocket division", an innovative maneuverable combined-arms formation. Because of high saturation with specialized troops and services it would have resembled a division, but in terms of manpower it would have been much smaller and amount to some 3,700 men.
Shortages of career officers and NCOs plus inability to provide arms and equipment needed rendered the original mixed brigade pattern unworkable. The Republican general staff kept redrafting the scheme with decreasing proportion of non-infantry sub-units, though even these arrangements proved impossible to implement. Most of the 188 mixed brigades raised during the war were closer to the infantry regiment blueprint.
Assumptions about the nature of the warfare which gave rise to the mixed brigade concept were largely correct. However, the Republic could not have afforded such highly-specialized and well-equipped units. Attempts to implement the scheme put extra strain on the Republican recruitment and logistics system; as a result, the mixed brigade scheme was counterproductive and worked to the detriment of the Republican military capacity.
Origins
Origins of the mixed brigade concept are not clear and in historiography there are various theories which point to its beginnings. One is related to debates within the Spanish general staff of the 1920s; banking on experiences of the Rif War, some officers suggested formation of relatively small, flexible combined-arms units.José Vicente Herrero Pérez, De la división orgánica a la brigada mixta (evolución de las grandes unidades en España 1914-1927), [in:] Revista de Historia Militar XLVI/93 (2003), p. 115 In the early 1930s and influenced by Swiss attempts,Michael Alpert, The Republican Army in the Spanish Civil War, Cambridge 2008, ISBN 9781107028739, p. 73 two Brigadas Mixtas were ordered to be formed as Spanish mountain troops.Herrero Pérez 2003, p. 116 During further discussions of the mid-1930s the idea that the Spanish army should include a large number of autonomous units smaller than división organica was gradually taking root.Herrero Pérez 2003, pp. 117-118
A somewhat competitive theory claims that the concept was merely an acknowledgement of warfare reality during first weeks of the Civil War. During July, August and September 1936 most fighting took place between improvised, relatively small, lightly armed and highly maneuverable groups, usually referred to as "columns". The Republican general staff reportedly concluded that they should turn this makeshift model into a systematic and structured scheme and units raised in this way should emphasize mobility and flexibility rather than manpower.Alpert 2007, p. 73; other authors tend to downplay the theory, compare Herrero Pérez 2003, p. 118 One more theory credits Soviet military advisers, present in Spain since early October 1936, for coining the concept;Alexander Clifford, The People's Army in the Spanish Civil War: A Military History of the Republic and International Brigades, 1936–1939, Philadelphia 2020, ISBN 9781526760937, p. 23 one version of this theory holds that the Soviets merely encouraged the Republican general staff to implement the idea which had already been in circulation for some time.Alpert 2007, pp. 73-74
Underlying concept: "pocket division"
The basic assumption which triggered emergence of the mixed brigade concept was that the war in Spain would be about flexibility rather than manpower. Such a vision elicited the idea that the key army unit should be able to operate independently, without support of other specialized units typically assigned to larger military formations (e.g. unlike a typical infantry regiment, which requires support of other divisional services to achieve military objectives). This in turn produced a conclusion that the key army unit should be a highly maneuverable, combined-arms formation.
The resulting vision was "a cross between a reinforced regiment and a very small division", Charles J. Esdaile, The Spanish Civil War. A Military History, London/New York 2019, ISBN 9781138311275, p. 100 a "little great unit",Clifford 2020, p. 28 "division en miniatura"Herrero Pérez 2003, p. 118 or a "pocket division": a unit which in terms of manpower would be much smaller than a division, but which would reproduce some of divisional features by means of large proportion of specialized and support sub-units. This vision was eventually embodied in a scheme of a "mixed brigade"; the term "mixed" was to indicate its combined-arms composition, making it different from a typical infantry unit of comparable size.Alpert 2007, p. 71 Mixed brigades were supposed to operate independently and to be grouped into a larger formation only for the purpose of waging a particular campaign or battle, but not as its permanent components.
Theoretical composition
The original scheme as worked out in 1936 envisioned that a mixed brigade would be made of 3,700 soldiers.Herrero Pérez 2003, p. 119 Internal composition was to be as follows:
brigade staff 4 infantry battalions. Each battalion was to consist of 4 infantry companies, 1 machine-gun company and 1 platoon of mortars. In comparison the regular army division, named "división orgánica", was composed of 2 brigades, each brigade composed of 2 regiments, each regiment composed of 3 battalionsHerrero Pérez 2003, pp. 112-113 1 field artillery group. It was to be composed of 4 batteries of medium artillery (usually 75 mm guns) and 1 battery of heavy artillery (usually 105 mm guns). In comparison the regular army division was to consist of 1 regiment of light artillery and 1 regiment of heavy howitzersHerrero Pérez 2003, p. 113 1 cavalry squadron (in alternative versions replaced with motorized infantry). In comparison the regular army division was also to include 1 squadron, on wartime footing enlarged to 1 cavalry regimentHerrero Pérez 2003, p. 112 1 pioneer company. The regular army division was to incorporate 1 battalion of pioneersHerrero Pérez 2003, p. 113 1 motorized reconnaissance squadronE. R. Hooton, Spain in Arms: A Military History of the Spanish Civil War, 1936–1939, London 2019, ISBN 978-1612006376, p. 43 1 communication and logistics group. It was to consist of dedicated communication (including radio transmission), intendancy and supply-logistics sub-units other support sub-units, including a sanitary and medical detachment
In terms of manpower the mixed brigade as originally envisioned was in-between a regular army infantry regiment and a regular brigade. In terms of firepower it would have been stronger than a brigade. In most European armies of the late 1930s (which unlike the Spanish army did not feature brigades as fixed divisional unitsmost armies of the mid-1930s followed a triangular pattern, with an infantry division composed of 3 regiments, a regiment composed of 3 battalions, and a battalion composed of 3 companies. Spanish division with its binar structure was a bit of an exception. Also, in most European armies brigades were specialized army units, e.g. cavalry brigades in the Polish army or panzer brigades in the Wehrmacht, though brigades were regular units of some British infantry divisions) it would have been comparable to a very strong regiment.German infantry regiment in 1917 was 3,832 men, W. Schilling, The Organization of Armies, [in:] Columbia service; Italian infantry regiment of early World War Two was 3,279 men, Regio Esercito. L'Organizzazione, [in:] RegioEsercito service; US infantry regiment of 1944 was 3,118 men, Regio Esercito. L'Organizzazione, [in:] RegioEsercito service; Polish infantry regiment of 1939 was 3,300 men, Zdzisław Jagiełło: Piechota Wojska Polskiego 1918-1939, Warszawa 2007, ISBN 9788311102064, p. 30; Wehrmacht infantry regiment of early World War Two was 3,049 men, Nigel Thomas, The German army in World War II, London 2002, ISBN 9781841766164, p. 10 In terms of modus operandi and because of its general autonomy a mixed brigade was somewhat resemblant of a division.
Implementation problems
Not a single unit has ever been raised in line with the original plan, all units named brigadas mixtas differed significantly and then very significantly from the scheme, and the entire original concept remained largely on paper. Initially the reason were pressing wartime necessities; the Nationalist army was approaching Madrid and half-formed units were thrown into battle before they reached the structure envisioned.Alpert 2007, p. 74 Later it turned out that the Republic was unable to provide all weapons and equipment needed, and that shortage of NCOs and officers made it impossible to ensure their sufficient number even for traditional army units. Finally, in later stages of the war the increasingly dramatic military situation forced Republican high command to raise troops in non-systematic, makeshift manner.Clifford 2020, p. 24
Because of problems with raising mixed brigades in line with the original plan, the Republican general staff was continuously re-drafting their structure; the change was generally about reducing the weight of non-infantry componentse.g. already in November 1936 the field artillery component was reduced to 3 batteries, plus antitank company and a mortar support group, Hooton 2019, p. 43 and enlarging infantry battalions (eventually from 633 to 828 men).Herrero Pérez 2003, p. 119 The result was decreasing firepower and increasing manpower of the entire unit; final versions of the brigada mixta scheme envisioned its strength as some 4,200 people, though less than a half would serve in frontline combat sub-units.Herrero Pérez 2003, pp. 119-120 However, neither these revised plans have been implemented and brigada mixta theoretical schemes as developed in 1937-1938 remained a blueprint intended, but never fully put into practice.Herrero Pérez 2003, p. 121
Practice
The concept of mixed brigades was discussed during sittings of the Republican government in late September 1936;Herrero Pérez 2003, p. 119 the first known military document which refers to raising of these units is dated 18 October 1936Herrero Pérez 2003, pp. 118-119 and the first 6 units were created shortly.they were commanded by 3 career army officers, 1 Carabineros officer, 1 civilian who underwent training in the Soviet military academy and 1 lawyer. Alpert 2007, p. 75 By December 1936 there were 15 brigades deployed,Hugh Thomas, The Spanish Civil War, London 2001, ISBN 9780375755156, p. 526 and by the spring of 1937 there were 40 units operational.Thomas 2001, p. 530 Those formed in central Spain were numbered 1-50, those raised in the Levante and Andalusia were numbered 51-82, whose those built in the North were numbered until 189.Alpert 2007, p. 75 The last brigade formed was numbered 246 and was created in December 1938,Carlos Engel Masóliver, Historia de las Brigadas Mixtas del Ejército Popular de la República, 1936-1939, Madrid 2005, ISBN 9788496170193, p. 228 though the number of units actually raised which entered combat was around 190.Herrero Pérez 2003, p. 125 Most of the build-up process was controlled by the military. Manpower was provided by distributing pre-war regiments among the brigades,Alpert 2007, p. 76 by incorporating earlier militia units active on the front, and then by regular draft (though there were also volunteers).