[1] In 1352, two Castilian envoys arrived at the French court seeking a marriage contract between Blanche and King Peter of Castile.

[2] Blanche's familial relationship as a niece of Philip IV and cousin to the current King John II were seen as advantageous by the cortes in Valladolid.

[4] She was greeted by Queen mother Maria On 3 June 1353,[a] aged 14, Blanche married in person at Valladolid, Spain, King Peter of Castile.

In 1361, Blanche was transferred to the town of Medina Sidonia, where she was kept distant from possible rescue by the forces from Aragon and France battling King Peter.

In 1361, after Peter had made peace with the King of Aragon, he returned to Seville and hoped to eliminate the last bastions of resistance to his rule.

Ayala, who had later joined with a winning faction led by Henry II, states that to Peter's anger, Estuñiga declined because the act was treasonous and likely to cause further disorder in the kingdom.

[8] During the 19th century, while Spain was ruled by the Bourbon monarchy, her tomb was provided with the following inscription in Latin: However, whether Peter did have her assassinated is a controversial claim.

On the other hand, Bourbon rulers had a stake in sanctifying the image of Blanche, a distant member of their ancestral lineage.