Do alliances/treaties between countries matter? Have they been invoked when required? Do they hold good in times of need? These are the questions that have been raised in the context of the Saudi-Pakistan Strategic Mutual Defence Agreement that was signed between the two countries on 17 September 2025. Under this agreement, both countries have committed to treating any act of aggression against one as an act against both. It is being likened to NATO, where an attack on one country is considered an attack on all. How the Saudi-Pakistan agreement plays out in the future, only time will tell. History, however, tells us that there are diplomatic treaties between countries that have endured and have been invoked by the signatories in times of need.
One such treaty that has withstood the test of time is the Treaty of Windsor, signed between Portugal and the United Kingdom in 1386. It is considered the oldest diplomatic alliance in the world. The treaty helped the Anglo-Portuguese relationship to survive wars, political upheavals, and even conflicting colonial agendas. From their joint efforts during the “Age of Exploration” to their struggle against Napoleonic forces, the alliance demonstrated its resilience and mutual benefit for both countries. The treaty then played an instrumental role in the Second World War and helped the allied forces to gain a foothold in the Portuguese Azores islands in the middle of the Atlantic Ocean. The opening led the Allied forces to control and then dominate the Atlantic Ocean, taking back from Germany the advantage it had established with its U-boats.
The Portuguese archipelago of the Azores, a group of nine volcanic islands, is situated in the North Atlantic about 1,500 km west of mainland Portugal and 3800 Km east of the eastern seaboard of the USA. For Germany in the Second World War, the Azores islands represented a potential base for U-boat operations, plus the possibility of air bases needed for ‘Projekt Amerika’, a planned Nazi Luftwaffe(Air Force) bombing campaign of America’s East Coast cities. With a base for provisioning in the middle of the Atlantic, U-boats would not waste so many days and fuel sailing out of and returning to their bases on mainland Europe. For the Allies, these islands were crucial to closing the "Mid-Atlantic Gap", an area where the German U-boats had established an area of dominance. It was a matter, of life and death. Since the beginning of the war in 1939 till the middle of 1943, the Allies had lost 2500 merchant ships, more than 15 million tonnes of shipping, over 200 escort warships, and about 30,000 lives in the Atlantic. In his memoirs, Winston Churchill wrote, "The only thing that ever really frightened me during the war was the U-boat peril," and “The U-boat attack was our worst evil. It would have been wise for the Germans to stake all upon it”. A foothold on the Azores islands was therefore vital to counter the German threat.
It was on October 12, 1943, that Churchill revealed to the House of Commons that he had invoked the 1386 ‘Treaty of Windsor’ with Portugal to grant facilities in the Azores to the UK to better protect merchant shipping in the Atlantic. He described the alliance as having lasted 600 years and that it is “without parallel in world history”. Between them, the Allies had agreed that the British would enter the Azores first, to be followed in two weeks by American forces. The British might come in under the treaty, and the Americans would follow according to the provision in the treaty that Britain and Portugal would be “friends to friends”. The Anglo-Portuguese agreement was effective from 8 October 1943, when the Royal Air Force (RAF) took over Lages airfield on the island of Terceira and began setting up 247 Group headquarters at the nearby Faial island. The Allied presence on the islands provided vital air cover and logistical support, enabling the Allies to target German U-boats, protect merchant convoys, and establish cross-Atlantic air routes. The bases drastically improved Allied capability to patrol the Atlantic. Losses of German U-boats increased significantly after long-range aircraft from the Azores began operating.
The direness of the situation was well expressed by the 1945 Nobel Peace Prize winner and U.S. Secretary of State (1933-1944) Cordell Hull, who is also known as the "Father of the United Nations”. He said, “Our whole democratic civilization twice hung by a thread during the recent war—once during the summer of 1940 after Dunkirk and the fall of France, when Britain even with her Navy might have failed to repulse a full-scale German attack across the Channel, and again during 1942, when German submarines were sinking three Allied merchant vessels for every one constructed”.
Churchill’s invocation of the 1386 treaty stands as a powerful example of how historical alliances can be used diplomatically in modern geopolitics. The Anglo-Portuguese treaty was again used by the United Kingdom in the Falklands War (1982). Portugal remained officially neutral in the conflict but allowed the UK Air Force to use the Azores for refueling, again citing the discretion offered by this alliance. However, the ‘Treaty of Windsor’ is not unique, and there exist other examples of bilateral treaties being invoked by countries. To cite a few, the 1839 ‘Treaty of London’ guaranteed Belgium’s neutrality by European powers. Germany violated it in 1914 by invading Belgium, and Britain entered World War 1, citing its obligation under the treaty. The 1960 ‘Treaty of Guarantee’ was signed by the UK, Greece, and Turkey to guarantee Cyprus’s independence and constitutional order. Turkey invoked it in 1974 and invaded Cyprus after there was a coup backed by the Greek military junta that it said threatened constitutional order. It resulted in Turkish occupation of about 37% of Cyprus, which continues till today.
India also got confidence from the 1971 ‘Indo-Soviet Treaty of Peace, Friendship and Cooperation’ during the India-Pakistan war of 1971. The USSR gave India diplomatic and strategic backing and deterred external intervention by sending naval assets to the Indian Ocean when the US seventh fleet moved towards India. The result of the war changed the map of the Indian subcontinent as India dismembered Pakistan and leading to the creation of an independent Bangladesh.
The author is Indian ambassador to Portugal. |
