Anglo-Portuguese Alliance
Alliance between the United Kingdom and Portugal, known for being the world's oldest alliance
The Anglo-Portuguese Alliance is the oldest alliance that is still in force by political bilateral agreement. It was established by the Treaty of Windsor in 1386, between the Kingdom of England and the Kingdom of Portugal, though the countries were previously allied via the Anglo-Portuguese Treaty of 1373. Since the signing of the Treaty of Windsor, the Kingdom of Portugal and the Kingdom of England, and later the modern Portuguese Republic and United Kingdom, have never waged war against each other, nor have they participated in wars on opposite sides as independent states. While Portugal was subsumed under the Iberian Union, rebellious Portuguese factions and government in exile sought refuge and help in England. England spearheaded the Anglo-Spanish War on the side of the deposed Portuguese royal house. Wikipedia