The deposed tyrant went to Bordeaux, where since 1363 the Black Prince had been resident as Prince of Aquitaine; for in 1362 Edward had erected his new possessions into a principality and conferred it on his eldest son, in the hope of conciliating the Gascons by some pretence of restoring their independence.  At Bordeaux Peter persuaded the prince to restore him to his throne by force.  Edward also agreed to support Peter, and sent his third son, John of Gaunt, to march through Brittany and Poitou with a powerful English reinforcement to his brother’s resources, while the lord of Aquitaine assembled the whole, strength of his new principality for the expedition.  At the bidding of his lord, Calveley cheerfully abandoned Du Guesclin, and thenceforth fought as courageously on the one side as he had previously done on the other.  Charles of Navarre professed great desire to help forward the invaders, and his offers of friendship opened up to the prince the easiest way into Spain by way of the pass of Roncesvalles from Saint-Jean-Pied-de-Port to Pamplona, the capital of Navarre.  In February, 1367, the prince’s army made its way in frost and snow through the valleys famous in romance.  From Pamplona two roads diverged to Burgos, the ancient Castilian capital.  The easier way ran south-westwards through Navarrese territory to the Ebro at Logrono, where beyond the river lay the Castilian frontier.  The more difficult route went westwards through rugged mountains and high valleys by way of Salvatierra and Vitoria to a passage over the upper Ebro at Miranda.  The Black Prince chose the latter route, and reached Vitoria in safely.  Beyond the town King Henry’s army held a position so strong that Edward found it impossible to dislodge him.

The winter weather still held the upland valleys in its grip when March was far advanced.  Men and horses suffered terribly from cold and hunger, and the prince, seeing that he could not long maintain his position, boldly resolved to transfer himself to the southern route.  A flank march over snow-clad sierras brought him to the vale of the Ebro, and, crossing the stream at Logrono, he took up his position a few miles south-west of that town, near the Castilian village of Navarrete.  On the prince’s change of front King Henry also moved southward, crossing the Ebro a few miles above Logrono, and then advanced to Najera, a village about six miles west of Navarrete, where he once more blocked the English path.  The prince, however, had the advantage of position and could afford to wait until the Castilians attacked.  On April 3 Henry advanced over the little river Najarilla against the enemy.  The Spanish host fought after a different fashion from that practised by both sides in the French wars.  Only Du Guesclin and the small remnant of the companies which still abode in Spain dismounted.  The mass of the Castilians remained on their horses.  Their cavalry was of two sorts:  besides a large number of men-at-arms