The Nationalists had also 220 modern aircraft on this front (70 of the Condor Legion, 80 of the Aviazione Legionaria and 70 Spanish), including many Bf 109 fighters.

[4] 14 August The Nationalist 1st Brigade of Navarre attacks the front between Valdecebollas (Palencia) and Cuesta Labra, trying to cut off the Republican forces south of the Cantabrian Mountains.

15 August The Nationalists advance in the area of Barruelo (Palencia) up to Peña Rubia, Salcedillo, Matalejos and Reinosilla; the Republic's fight back at Portillo de Suano.

23 August Navarrese forces enter Mazcuerras Valley and take Mount Ibio, nearly cutting the main road and railway between Santander and Asturias.

Santander's fall, coupled with the capture of heavily fortified Bilbao, tore an irreparable gap in the Republic's northern front.

The destruction of the Army of the North marked another crippling blow to the Republic's sagging strength and turned the war to Franco's favour.

In no other theatre of the civil war did Franco's troops achieve results as decisive as those of the Santander campaign: sixty thousand Republican soldiers were wiped off the map, with corresponding losses in materiel.