Portugal during World War II
Upon the start of World War II in 1939, the Portuguese Government announced on 1 September that the 600-year-old Anglo-Portuguese Alliance remained intact, but that since the British did not seek Portuguese assistance, Portugal was free to remain neutral in the war and would do so. In an aide-mémoire of 5 September 1939, the British Government confirmed the understanding. As Hitler's occupation swept across Europe, neutral Portugal became one of the Continent's last escape routes. Portugal managed to remain neutral throughout the war despite extraordinary pressures from both sides, notably over the strategically located Azores islands and over the wolfram (tungsten) trade.
Continental System
Portugal openly refused to join the Continental System. In 1793, Portugal signed a treaty of mutual assistance with Britain. After the Treaty of Tilsit of July 1807, Napoleon attempted to capture the Portuguese Fleet and the House of Braganza, and to occupy the Portuguese ports. He failed, as king John VI of Portugal took his fleet and transferred the Portuguese Court to Brazil with a Royal Navy escort. The Portuguese population rose in revolt against the French invaders, with the help of the British Army under Arthur Wellesley, later 1st Duke of Wellington. Napoleon intervened, and the Peninsular War began in 1808. Napoleon also forced the Spanish royal family to resign their throne in favor of Napoleon's brother, Joseph.