The bulk of the security forces in Madrid remained loyal to the government, and supported by workers' militias, crushed the uprising.

There was no coordination between the diverse elements who were hostile to the republic – falangists, monarchists, some army officers, and members of the Spanish Military Union.

The coordinator of the plot in Madrid, Colonel Valentín Galarza Morante had been detained and the elderly and indecisive General Villegas took his place.

Finally, a large portion of the officers and soldiers of the regular Madrid army garrison were uninvolved in the plot and pre-disposed to remain loyal to the elected government.

[2] Located on the Príncipe Pío near the former Royal Palace of Madrid to the west of the central city, the Montaña barracks had been built in 1860.

On 18 July, news of the military uprising in Spanish Morocco reached Madrid, and the General Union of Workers and National Confederation of Labor demanded the distribution of arms.

[7] On 19 July, the new government of Prime Minister José Giral decided to issue weapons to the unions; 65,000 rifles were handed over, but only 5,000 had bolts.

The commander of the barracks, Colonel Moisés Serra, disregarded the order of the Minister of War to hand over this essential equipment, effectively marking the beginning of the uprising in Madrid.

[8] On the morning of 19 July, General Fanjul arrived at the Montaña barracks, as did groups of officers from the other Madrid garrisons and a number of falangist and monarchist volunteers.

In Carabanchel, General García Herrán had been killed by his own troops while trying to raise them against the government and the artillery barracks there had been secured by loyalist officers.

Against the orders of Lieutenant Moreno of the Assault Guards, who were leading the attack, the crowd ran forward but other defenders fired at them from the barracks with machine guns.