In the small Battle of Aríñez (Basque, battle of Inglesmendi, Battle of the English Mount) in the third week of March 1367, a vanguard of Henry's army formed by jinetes (Castilian light cavalry) led by Don Tello and Aragonese and French knights led by Arnoul d'Audrehem, Pierre le Bègue de Villaines and Juan Ramirez de Arellano wiped out a detachment of the Black Prince's army. Henry's vanguard easily defeated groups ahead of the bulk of the army of the Black Prince by skirmishes and then headed back to their base. On their way, they met with an exploration detachment of the Black Prince's army, which was led by the Seneschal of Aquitaine Sir Thomas Felton with 200 men-at-arms and archers. After suffering many casualties, the detachment of the Prince of Wales entrenched in the mountain of Inglesmendi, where the English longbowmen resisted the Castilian light cavalry. The French and Aragonese soldiers dismounted and attacked as infantry, defeating them. There died, among others, Sir William Felton, Seneschal of Poitou and captain of great companies; many others were captured, Thomas Felton, the captain of great companies, Richard Taunton, Sir Hugh Hastings, the military Lord John Neville, the captain of great companies Aghorises and the Gascon mercenary captain of great companies Gaillard Vighier (or Beguer), among others. The army of the Black Prince that had hitherto been considered invincible, had suffered its first defeat and although their losses were not large in comparison with the large army, the troops began to become demoralized. The Black Prince mobilized his troops to approach Burgos —his goal— from Vitoria, but Henry stepped ahead and blocked his path which forced the army of Peter to retreat again. At the end of March the Black Prince crossed the Ebro at Logroño, where he made a camp. Henry again blocked access to Burgos by controlling the river Najerilla. The political situation was quite different; more people adhered to the cause of Peter that gained strength, while his alliances weakened, because avoiding confrontation was seen as a sign of weakness by the Castilian nobility. Time was playing against the ambitious Henry, who advanced with his forces, leaving behind the protection of the river Najerilla to confront his half-brother. To prevent disaster, he had to face the most prominent mercenary troops of Europe, outnumbered, in a battle in the open and with the river in his back cutting his retreat, despite