[5] King Louis IX's marriage to Margaret had been arranged by his mother, Blanche of Castile, with the hopes that he would inherit Provence and Forcalquier when her father died.

In his will signed on 20 June 1238 at Sisteron,[6] Ramon Berenguer IV unexpectedly left the Counties of Provence and Forcalquier to his youngest and still unmarried daughter, Beatrice.

Firstly, the neighboring rulers of her domains began their claims: the twice-divorced Raymond VII, Count of Toulouse and King James I of Aragon, who, despite being married to Violant of Hungary, invaded Provence and seized the residence of the countess.

[8] In addition, the thrice-widowed Frederick II, Holy Roman Emperor, dispatched the imperial navy to Provence to ensure Beatrice could marry one of his sons or even himself.

In such a difficult situation, the Dowager Countess decided to act quickly, placing herself and Beatrice in a safe fortress in Aix, secured the trust of its people and then asked Pope Innocent IV for his protection.

In Cluny during December 1245, a secret meeting between Pope Innocent IV, Louis IX of France, his mother Blanche of Castile, and his youngest brother Charles took place.

Henry III of England protested these terms, arguing that he had not yet received the full dowry for his wife Eleanor nor his brother for Sanchia.

The inheritance of Beatrice also caused conflicts with her older sisters, who hoped that once their father had died, his domains would be divided between the four; Charles refused to share the Counties with his sisters-in-law.

Charles and Beatrice, along with several other nobles, left soon after and journeyed to the court of Emperor Frederick II, to ask him to send the King of France more men for his crusade.

She called on all her knights as well as the young men of France, and according to the later historian Angelo di Costanzo she pledged all her jewels, to make sure they joined her husband's army: Beatrice, to aid [Charles] in the gratification of her ambition, sold all her jewels and personal ornaments, and expended her private treasure in collecting round her standard, not only her own vassals, but the chivalric youth of France, who were attracted to her service not less by her personal solicitations than by her rich gifts.

[17]In 1265 Charles of Anjou, with a small contingent, embarked and by sea arrived in Rome, where, on 28 June, he was invested as King of Sicily by the Pope.

[20] As soon as the coronation festivities had ended, Beatrice stayed in Rome with a small force to hold the city, whilst Charles rode out to the battle of Benevento.

Beatrice died on 23 September 1267, a little over a year after becoming queen[21] in either the Castello del Parco at Nocera Inferiore or in Naples (according to the storia di Saba Malaspina[22]).