Catherine was born at the Ducal Palace of Vila Viçosa, as the second surviving daughter of John, 8th Duke of Braganza and his wife, Luisa de Guzmán. Following the Portuguese Restoration War, her father was acclaimed King John IV of Portugal, on 1 December 1640. With her father's new position as one of Europe's most important monarchs, Portugal then possessing a widespread colonial empire, Catherine became a prime choice for a wife for European royalty, and she was proposed as a bride for John of Austria, François de Vendôme, duc de Beaufort, Louis XIV and Charles II. The consideration for the final choice was due to her being seen as a useful conduit for contracting an alliance between Portugal and England, after the Treaty of the Pyrenees in 1659 in which Portugal was arguably abandoned by France. Despite her country's ongoing struggle with Spain, Catherine enjoyed a happy, contented childhood in her beloved Lisbon.