[3] Alfonso was a son of Infante Sebastian of Portugal and Spain and his second wife, Infanta Maria Christina.

In 1929, he morganatically married Julia Méndez y Morales, losing all claims to the Spanish throne; the marriage remained childless and ended in divorce.

In 1868, a revolution forced him and his family into exile, and they settled in the French town of Biarritz.

After completing his education and returning to Spain, Alfonso declined a ducal title offered by the Regent Queen, as he believed it would diminish the significance of his noble lineage as the child of two Spanish infantes and would overshadow the prominence of the Borbón name.

[5] In 1929, Alfonso married Julia Méndez Morales in San Sebastián, but the marriage ended in divorce with the advent of the Second Spanish Republic.