Question: What is the date of death of Philip Prospero, Prince Of Asturias's mother?
Sentence (from "Philip Prospero, Prince of Asturias"): Philip IV had no male heir since the death of Balthasar Charles, his son by his first wife, Elisabeth of France, eleven years before, and as Spain's strength continued to ebb the issue of succession had become a matter of fervent and anxious prayer.
Relevant evidence: No