Towards the end of September 1936, communist parties of different countries received instructions from the Comintern and from Moscow for the recruitment and organization of the International Brigades, which would enter active combat during the month of November. Meanwhile, the successful conclusion of the Siege of the Alcázar on September 27 in favour of the Nationalist side allowed the forces of General José Enrique Varela to concentrate their efforts on the Siege of Madrid.