This battle was fought in 20mm in a morning and afternoon.

Frustrated in their attempt to directly take Madrid, the Nationalists launched the first of their major flanking offensives that would culminate in the Battle of Guadalahara. The Nationalist attack, designed to cut Madrid off from the Guadarrama Mountains and surround it from the north, began with heavy bombardments and fierce infantry advances backed by light tanks. From the middle of December, Nationalist columns pushed Republican units back again and again to the limits of the town of Pozuelo de Alarcón.

Reacting to the Nationalist move, Madrid sent reinforcements in the form of Russian tanks under General Pavlov and International Brigade troops. Republican troops were pushed back again and again as Nationalists advanced to capture the southern part of the town of Pozuelo de Alarcón. The Republican 3rd Mixed Brigade, having borne the brunt of the attack, inflicted terrible casualties on the advancing Moroccan troops, who advanced into the slaughter of numerous machine gun nests. Still, the weight of the attack all but annihilated the 3rd Brigade, forcing its remnants to fall back behind the lines of the reinforcing Internationals. The Polish and Italian troops of the XIth International Brigade fought with distinction, taking heavy casualties, yet mowing down the Moroccans who continued to advance steadfastly into the fire of the Internationals' machine guns and rifles. Meanwhile, Nationalist cavalry and German tanks proved no match for the Russian T-26's. The incredible death toll finally forced the Nationalists to halt and regain their strength. The Republic lost about 15,000 men during the battles; the Nationalists lost as many men, and managed to seize about ten miles of highway with the town of Pozuelo. The Nationalist offensive had been stopped.