 However, the Nationalists' attack on the capital was repulsed in fierce fighting between 8 and 23 November.A contributory factor in the successful Republican defense was the effectiveness of the Fifth Regiment and later the arrival of the International Brigades, though only an approximate 3,000 foreign volunteers participated in the battle.Having failed to take the capital, Franco bombarded it from the air and, in the following two years, mounted several offensives to try to encircle Madrid, beginning the three-year Siege of Madrid.