As Spain started to make its first steps as a democratic and open country after 36 years of Franco's dictatorship, the treaty of friendship and cooperation with the USA was signed on 24 January 1976. Diario SUR's front page headline the following day simply read, 'The Treaty Was Signed'.
The newspaper reported that at 12.30pm, then American secretary of state Henry Kissinger's plane landed at Madrid's Barajas airport, where he was met by the Spanish foreign minister, José María de Areilza.
From there the two men, accompanied by other government representatives from both countries, travelled to the Zarzuela palace where Kissinger met and had lunch with King Juan Carlos I.
The party went on to the Santa Cruz palace where, at 6pm, Areilza and Kissinger signed the treaty. Once signed, the two men exchanged the fountain pens they had each used.
Fifteen minutes later, international journalists were allowed into the palace, where the two men gave a press statement and answered questions.
Both politicians alluded to the importance of the treaty at a time when Spain was entering a new era of democracy and opening its doors to the rest of the world.
"I consider this act to be of great importance for the political and diplomatic history of Spain," said Areilza.
He went on to say, "This treaty represents the firm will of Spain to no longer live in international isolation, but to live in the interconnected world of today, an interdependent world which obliges us to maintain international relationships with the rest of the world."
Kissinger echoed Areilza words, saying, "Today's events have happened at a time in which Spain is experiencing the emotion, inspiration and challenge of a new era."
He ended his speech by saying that the treaty showed Spain the "support of the USA" as it entered a new era.
While the treaty signed on 24 January 1976 was the seventh of its kind between the two countries since the USA gained independence in 1776, both men considered it to be the most "far reaching and comprehensive".
The historic day ended with a dinner at the Viana palace which was attended by Areilza, Kissinger, the Spanish and US ambassadors and other representatives from both delegations.