No passaran! The people of Madrid on the barricades.

Years 1919-1939, commonly called "years of peace", in fact were abundant in armed conflicts, and even wars of different scale and intensity. Among the biggest ones was the Spanish Civil War (1936-1939). Its classification among the biggest military conflicts of the inter-war period came out of both its intensity, and political significance. In that war clashed large regular armies; it also became a shooting range, where were tested new weapons and equipment, as well as new tactical concepts of warfare. In particular, it was the German Wehrmacht that treated Spain as an excellent range, furnishing an opportunity to test the military doctrine on the eve of preparations for the war for the European and world domination.

Political significance of the Spanish Civil War was in the attempt of democratic forces to stand against growing fascist expansion. That is why the rebels had gained support from Nazi Germany and fascist Italy, while the progressive world supported the legal government. That is why the civil war in Spain became a revolutionary war. Radical moods, and the need to mobilize broad social masses, created the necessity of far-going reforms and social transformations.

Fascist states, and trans-national corporations were supporting the rebels, fighting for destruction of the republic, and introduction of totalitarian, fascist dictatorship. On the other side were blocked supporters of democratic processes, evolving towards radical transformations, and progressive forces backed by the first socialist state, the Union of Soviet Socialist Republics, which provided political support, weapons, and all materials that the Spanish republic needed to conduct the struggle.

Finally, the Spanish civil War is of interest to military historians, due to its specific character. During tits initial phase, which lasted till November 1936, it was a mobile war, conducted by small forces in vast operational zones. At that time it was not possible to create stable, continuous fronts, and engaged forces were limited. Their objective, as a rule, was to capture main cities and administration centres. It was so-called column's war. The name comes from columns of thousands of soldiers that both sides used to form to operate in individual, isolated sectors, and endeavour to seize designated objects. There was no centralized command at that stage. Improvising dominated the hostilities.

As the fascist régimes of Italy and Germany came to the aid of the rebels, first with transporting Moroccan troops to Spain, and then with open intervention in the Spanish civil war, fascists were first to come out with a uniform plan of waging the war. Its first stage foresaw joining isolated operational zones remaining under the control of the rebel forces, and then concentration of all fascist forces for the final objective, which was Madrid. At the same time republicans, mainly due to incompetence of consecutive governments, had no clear and uniform strategy, and did little to organize armed forces. Parties forming the Popular Front constantly quarrelled over the basic principles of organization of the republican army. With time two of them became particularly popular and gained most of the supporters. The first one, proposed by socialists, provided for creation of a popular militia made of armed volunteers. The other one, advocated by communists, called for a regular, professional army. The war proved that the communists were right: popular militia lacked professionalism and combat spirit in fights with regular rebel troops, and its defeats menaced with a total annihilation of the republic.

In August 1936, after isolated rebel zones merged into one area under uniform control, the commander of the rebel forces, Gen. Francisco Franco Bahamonde, planned to take Madrid. It was the rebels' strategic plan that was supposed to lead them to a swift victory and annihilation of the republic. Yet, factional fights among the fascist leaders postponed that plan till October 1936.

Franco - already as the sole fascist leader - began realization of his plan on 6 October 1936. He expected that it would be a swift campaign, and his forces would march into Madrid on 7 November - the anniversary of the Great October Socialist Revolution in Russia. But the reality proved different. The danger of overthrowing the republic had united and mobilized the Spaniards. The concept of the professional army gained a broad popular support, and the government was forced to start formation of the regular units, and undertake other measures to build up the republican military potential.

Active engagement of the German and Italian regular forces on Franco's side caused that volunteers from 54 countries rushed with aid to the Spanish republic. During the whole war somewhere between 35 and 42 thousand of them fought on the Spanish soil. In different periods of the war that constituted from 4% to 15% of the republican People's Army, and could not balance the aid delivered to the rebels by the fascist governments of Germany and Italy, but at the very difficult time of the battle for Madrid international volunteers came as a substantial reinforcements of the fighting troops. The biggest merit of the International Brigades (formed since 22 October 1936) was to set a practical pattern of organization and training for newly formed republican units.

Upon the dramatic appeal of the Spanish government to the world's public opinion for help in the struggle with domestic rebellion and international fascist intervention, the Soviet Union was the first country to answer positively. During the particularly difficult first weeks of the defence of Madrid it provided modern military equipment (tanks and aircraft), and allowed Soviet military specialists to volunteer for Spain and help with organization of the republican army.

Consolidation of the Spanish army and society in the defence of their capital brought spectacular effects. The first fascism offensive on Madrid collapsed on 16 November 1936. The "lightning war" that Franco announced did not happen. After the first shock that the defence of Madrid became to the fascists, they did not abandon their design, and in mid-January 1937 they launched another offensive. It failed too. The young Popular Army started gaining combat experience and increasing systematically its strength. It allowed for formation of divisions comprised of several brigades, which in the initial phase of the battle for Madrid were the biggest combat units of the republican army.

In February 1937 Franco launched the third offensive on Madrid. This time the design was to lure the defenders out of the city and crush them in open. There took place the battle of Jarama. In the course of pitched and bloody fights the fascist offensive was brought to halt. That meant fiasco of another plan to take the capital. Those were not republican forces, which bled in the battle of Jarama, as Franco expected, but his own cadre units.

Therefore, to the fourth offensive was assigned the Italian Corps of Volunteer Troops composed of three well trained and supplied infantry divisions and one armoured division. This way fascist Italy had marked its involvement in the Spanish civil war on Franco's side without taking care of appearances.

In March 1937 began the battle of Guadalajara near Madrid. After the initial Italian success the republicans mobilized necessary reinforcements, halted, and then forced the Italian corps to retreat. This way the fourth attempt to take Madrid had completely failed. The Italians had suffered a miserable defeat.

Gen. Franco's four major offensives on Madrid failed and the young People's Army proved its combat worthiness. It was the triumph of the Soviet model of the army. From then on, on the republican side were formed big tactical and units - corps. It meant further development of the People's Army. Francoists were forced to change their whole strategy - after the battle of Guadalajara they gave up attempts to take Madrid, and concentrated their efforts in the northern provinces of Spain.

Yet, the battle for Madrid did not end in March 1937. Although the fascists gave up the plans to take Madrid directly, such a danger was still clear and present. In the summer of 1937 the republicans tried to relieve the Northern Front and the capital city again found itself in the thick of military operations. In July the republicans launched a counter-offensive near Brunete in order to push the enemy from Madrid. In case of success, the immediate danger to the city would be dismissed. Yet, the Brunete operation, although relieved the Northern Front, failed to bring any substantial changes in the frontlines, and failed to push the enemy away from the suburbs of Madrid.

The battle of Brunete closed the battle of Madrid; since July 1937 till March 1939 no major military operations were conducted in that sector. Nevertheless, the battle of Madrid was of big importance to the Spanish Civil War. Efficient defence of the capital forced the fascists to reconsider their strategic plans, and determined the character of the further military operations. The defence of Madrid made the first significant breach in the concept of "lightning war" before it was implemented in the battlefields of the Second World War. It stalled the manoeuvre and transformed the war into trench warfare. Yet, the opposing sides did not give up manoeuvre operations. However, their offensive operations had limited range and local importance; the war was becoming protracted, and the strategic objective of the opposing sides became not annihilation of the enemy forces in a decisive battle, but such an economical attrition of the enemy, which would deteriorate his ability to wage the war. Francoists were able to impose the war of attrition on the republicans because they were drawing on practically unlimited support of Italy and Germany. On the other hand the Spanish republic was deprived of the possibility to buy weapons and supplies due to the non-intervention policy proclaimed by France and Great Britain, and many other countries of Europe and the world. In such an international isolation the Spanish Republic had no chance to win the war of attrition.

The battle of Madrid also contributed new experience to the modern warfare, and constituted a very significant prelude to the Second World War in this respect. Particularly valuable was the experience in preparation and conduct of defence of big urban areas. The battle of Madrid had proved that in the modern warfare efficient anti-tank and anti-aircraft defence played a crucial role. Republican counter-offensives in January (Algora and Almadrones) and March (Guadalajara) 1937 brought particularly interesting conclusions. There for the first time in the history of human conflicts was organized co-operation and co-ordination of big masses of main branches of service: infantry, armour and air forces.

Republican forces in defence of Madrid were able to neutralize the enemy's superiority in manpower through efficient use of the operational factors, which utilized concentration of technics in the axes of attack and the element of surprise. During their counter-strikes and counter-offensives they started to pursue outflanking the enemy and striking against its rears as opposed to the traditional frontal attack applied on the fascist side.

During the battle for Madrid fascists, and especially the German air squadrons from the Condor Legion, practically tested relevance of the theory of the air war by Gen. Giulio Douhet, who in 1921, in his book Command of the Air, formulated the theory that the air forces can independently achieve strategic objectives of a war, that is the victory over the enemy. Therefore, within 52 days they carried 30 air raids on Madrid, each engaging 20 to 50 bombers carrying about 50 tons of bombs. It turned out that intensive bombing alone does not lead to the victory. On the other hand, in the battles of Jarama and Guadalajara the tactical support to the ground troops demonstrated its practical advantage.