Spain allied with France in 1761 during the final phase of the Seven Years’ War.
The alliance was formalized through the Third Family Compact, signed on August 15, 1761, by France’s Louis XV and Spain’s Charles III. Both monarchs belonged to branches of the Bourbon dynasty, and the agreement reflected their shared concern about Britain’s growing military and colonial power.
Spain had initially stayed out of the war, but French diplomacy and British victories changed the calculation. Charles III feared that a French defeat would leave Britain too dominant in the Atlantic and threaten Spanish possessions and trade. The compact promised cooperation and required Spain to support France if the conflict continued beyond a set deadline.
Spain did not immediately declare war in 1761. Tensions escalated through late 1761, and Britain declared war on Spain on January 4, 1762. Spanish forces then fought Britain in Europe and overseas, including campaigns involving Cuba, the Philippines, and Portugal.
The Spanish intervention came too late to rescue France. The Treaty of Paris in 1763 ended the wider conflict; Spain ceded Florida to Britain but recovered Cuba and received Louisiana from France.