Within hours the Nationalist artillery silenced most of the Republican batteries, but when the troops advanced according to plan, not only did they encounter totally unexpected resistance, but they had to meet a well-executed counterattack.; supported by Soviet tanks and artillery. The progress slowed and then stopped.
Varela was furious:"We must break through at all costs", he ordered. The fight resumed, the two parties fighting with a ferocity and courage rarely equaled:a Moroccan tabor which, bayonet fixed, had launched the assault without worrying about the losses, was annihilated to the last man; on the Republican side, a battalion of women held a vitally important bridge, the children helping to rebuild the demolished barricades and the dead serving to reinforce the parapets. At the posts signaling that they were firing their last cartridges, the answer was to continue to hang on at all costs for twenty-four hours until reinforcements arrived.
By midnight on November 7, although the Nationalist troops had penetrated deep into the center of Madrid, a decisive break in the lines had not yet been achieved and the defenses were still intact. More importantly, a new mindset was taking shape in Madrid; hope, almost extinguished, was reborn against all logic.
On Sunday, November 8, around noon, men could be heard in Madrid singing a marching song in chorus. Soldiers in velvet uniforms and wearing blue helmets marched up the Gran Via in a column of fours. They were the 1,900 men of the international brigade, made up mainly of Poles, Germans and French.
They sang the Internationale in half a dozen languages and the The people of Madrid, assuming that they were the vanguard of a large Soviet force, cheered them endlessly.
These reinforcements were immediately sent in line; the Poles at Villaverde to the south of the town, half of the Germans and a group of English machine-gunners at the Cité Universitaire on the heights to the north-west and the French battalion as well as the rest of the Germans due west, on the other side of the Manzanares River and within 15 square kilometers of Madrid's hilly wooded park, the Casa de Campo.
Dominated by Mount Garabitas, some 2,500 meters from the University City, the Casa de Campo was one of the main targets of the nationalists. Their plan was to clear the park, force the defenders to recross the Manzanares, and seize the Montaria barracks. Contrary to their expectations, they were held in check by a powerful counter-attack and only succeeded in gaining the heights of Mount Garabitas. It was, nonetheless, a sizeable gain, and the Nationalists were able to cling to it for the duration of the war.
To boost Republican morale and improve their military proficiency, the men of the international brigade on the basis of one for every four men of the Militia. Trenches were dug, machine guns reinstalled while every attempt at Nationalist outflanking was immediately countered. Some French from the International Brigades had fought in Verdun and the Madrid "no pasaran" ("They will not pass") found an echo in their hearts.
The soldiers of the African army were constantly called upon; on the Republican side, the men, poorly trained, advanced unprotected under deadly machine gun fire while the International Brigades fiercely defended almost untenable positions:the losses on both sides were very high.
In three days, one in three of those who had come up singing the Gran Via had been killed. As for the army of Africa, it had, during these combats, more deaths than it had had during all the long march from Cadiz to Madrid.
An anarchist column , who had covered herself with glory in the open countryside in Catalonia, broke into the streets of the city, seized with panic as she fell under the fire of concealed machine guns; it let the nationalists cross the Casa de Campo, cross the Manzanares and enter the University City. There the fight turned into a nightmare. Nationalists sometimes occupied one floor of a university building, Republicans one above or below; sometimes even the men of the International Brigades were in one room and the legionnaires in the next one. Walls and floors were ripped open with pickaxes, and thrown grenades were sometimes sent back.