He had never come to draw his sword against France, and certainly no loss had been suffered by France in consequence of any action of his.

Louis's army was definitely routed at Garigliano, with Cesare's troops fighting in its ranks.
But Pope Alexander was dead; Cesare's might in in Italy was dissipated; his credit gone.

There lay no profit for Louis in keeping faith with him; there lay some profit in breaking it.

Alas, that a king should stain his honour with base and vulgar lies to minister to his cupidity, and that he should set them down above his seal and signature to shame him through centuries still in the womb of Time! Cesare Borgia, landless, without right to any title, he that had held so many, betrayed and abandoned on every side, had now nothing to offer in the world's market but his stout sword and his glad courage.

These went to the first bidder for them, who happened to be his brother-in-law King Jean.
Navarre at the time was being snarled and quarrelled over by France and Spain, both menacing its independence, each pretending to claims upon it which do not, in themselves, concern us.
In addition, the country itself was torn by two factions--the Beaumontes and the Agramontes--and it was entrusted to Cesare to restore Navarre to peace and unity at home before proceeding--with the aid upon which he depended from the Emperor Maximilian--to deal with the enemies beyond her frontiers.
The Castle of Viana was being held by Louis de Beaumont--chief of the faction that bore his name--and refused to surrender to the king.
To reduce it and compel Beaumont to obedience went Cesare as Captain-General of Navarre, early in February of 1507.