The Nationalists tried to isolate Madrid from the west, cutting the Corunna Road, but the Republican army repelled the attack.

After the failure to take Madrid in November 1936 and the failure to reduce the morale of the city's population through aerial bombing, Franco decided to encircle the city from the north-west in order to cut off water and electricity supplies from the Sierra de Guadarrama.

Franco's Nationalists, led by José Varela, concentrated a force of 3,000 men supported by heavy artillery including Ju 52 bombers.

[1] The Nationalist offensive started on 29 November with heavy artillery bombing on the Pozuelo sector with 3,000 Legion and Moroccan colonial troops backed by tanks and Ju 52 bombers.

[1] The Nationalists only occupied Boadilla del Monte and Villanueva de la Cañada and failed to cut Madrid from the north.