This lasted until 1943, when, after three months' negotiations, it was fully reactivated by the National Government of Winston Churchill and Portugal.

[6] Britain was accorded aerodrome and nautical facilities in the Portuguese Azores to help combat the U-boat threat.

[citation needed] The 650th anniversary of the treaty was officially commemorated by the governments of both nations on 16 June 2023, and in acknowledgement that this represents "the world's longest diplomatic alliance".

[8] A famous passage in the treaty assures that:[9][10] [t]here shall be between the respective kings and their successors, their realms, lands, dominions, provinces, vassals, and subjects whomsoever, faithfully obeying, true, faithful, constant, mutual, and perpetual friendships [Amicitae], unions [Adunationes], alliances [Alligantiae], and leagues of sincere affection [purae Dilectionis foedera]; and that, as true and faithful princes, they shall henceforth reciprocally be friends to friends and enemies to enemies, and shall assist, maintain, and uphold each other mutually, by sea and by land, against all men that may live or die of whatever degree, station, rank, or condition they may be, and against their lands, realms, and dominions.In 1943, the Portuguese Government leased to Britain what became a major Allied air and naval base in the Portuguese islands, the Azores.

Prime Minister Winston Churchill recounted reporting on the lease to the House of Commons: "I have an announcement", I said, "to make to the House arising out of the treaty signed between this country and Portugal in the year 1373 between His Majesty King Edward III and King Ferdinand and Queen Eleanor of Portugal.