The Spanish invasion of Portugal between 5 May and 24 November 1762 was a military episode in the wider Seven Years' War in which Spain and France were defeated by the Anglo-Portuguese Alliance with broad popular resistance. It involved at first the forces of Spain and Portugal until France and Great Britain intervened in the conflict on the side of their respective allies. The war was also strongly marked by guerrilla warfare in the mountainous country, which cut off supplies from Spain, and a hostile peasantry, which enforced a scorched earth policy as the invading armies approached that left the invaders starving and short of military supplies and forced them to retreat with heavy losses, mostly from starvation, disease, and desertion.