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.
Portugal–United Kingdom relations
The 19th century saw the alliance between Portugal and the United Kingdom come into effect once more when Napoleon Bonaparte built the Continental System, which Portugal refused to join, leading Napoleon to invade. In 1807 Napoleon's army attacked Lisbon, forcing the Portuguese royal family to flee to Brazil under the protection of the British Royal Navy. In the later half of the century, as Portugal's imperial power declined following Brazil's independence, there were disputes between itself and the United Kingdom in southern Africa (1890 British Ultimatum) which was a great embarrassment for the Portuguese monarchy and colonial prestige. Portugal was one of the Allies of World War I along with Britain. While officially neutral in World War II, Portugal remained friendly to the British, a counterpart to Spain's cooperation with the Axis.