She was the daughter of Marguerite of Cauna and of Paul, Baron of Andoins, Lord of Lescar, Viscount and later Count of Louvigny.

Philibert died of a wound received in 1580 during the siege of La Fère in Picardy,[1] and Diane found herself a widow at the age of 26.

[1] She fell in love with courtly literature, and it was in the chivalric romance Amadis de Gaula that she found a heroine that she could identify with, and whose name she adopted: "Corisande".

During the Wars of the League, she sold her diamonds for him, pawned her possessions, and went so far as to send out to him an army of 20,000 Gascons whom she had enlisted at her expense.

She was probably the cause of the disfavor of Françoise de Montmorency-Fosseux (Henry's previous mistress from 1579 to 1581) and Protestants worried about the influence of this Catholic on the sovereign of Béarn.