After John III's 1516 failed reconquest attempt, his son and legitimate heir apparent to the throne of Navarre, Henry II, saw an option through to reconquer the kingdom now the Castilian army was busy dealing with the Revolt of the Comuneros.

He sent a large French/Navarrese army commanded by General André de Foix,[1] Lord of Lesparre, (or Asparros or Esparre) across the Pyrenees, consisting of 12,000 infantry, 800 mounted knights, and 29 pieces of artillery.

In the meantime the Revolt of the Comuneros had been crushed at the Battle of Villalar in April, and the Spanish were able to gather a huge army of 25,000 men and moved on Navarre.

The Spanish troops had grown to more the 30,000 men under command of Iñigo Fernández de Velasco, Constable of Castile and the Duke of Nájera, viceroy of Navarre.

But then Fadrique Enríquez, Admiral of Castile, moved his cavalry across the Sierra de Erreniega and fell upon the Franco-Navarrese rear guard.