[4][6][7] During his four years there, he developed a deep interest in football, becoming one of the best players in his school since he had great skill in dominating the ball and in dribbles, two virtues that were highly regarded in a time when kicking reigned.

[10][11][12] At first, he became a member of an informal group led by Carlos and Manuel Castellanos, the so-called Bilbao Football Club, becoming an important piece when it came to arranging meetings between them and the workers from the Nervión shipyards.

[6][11] Gimnásio Zamacois, the largest sports center in Bilbao at that time, and the Velocipedista Club, where Astorquia maintained friendships due to his militancy as a member, inevitably became the main sources of recruitment, and thus, once added a sufficient number of volunteers, he began to arrange and organize football matches against the British workers, which were contested on Sundays in Lamiako.

[6] Although it was founded in 1898, it was not until February 1901, in a meeting held at the Café García, that Astorquia's group, now larger, began conversations to become an official football club.

[11] To achieve this result, a commission made up of Astorquia, Goiri, and José Maria Barquín was formed to prepare regulations for a football society, which were approved on 11 June.

[11][12][13] Since the figure of coach as we know it today did not exist at the time, it was Astorquia and Mills, as captains of the clubs, who were in charge of making up the line-ups and dictating the tactics to be followed.

Astorquia then used Bizcaya's successful campaign at the Copa de la Coronación to convince the newly-elected president of Bilbao FC Luis Arana of how beneficial and necessary it was to merge the two clubs permanently, and in order to further convince them of the merger, he promised to pass down the torch of the presidency to a Bilbao FC associate, Enrique Careaga.

[6] Once the negotiations had begun, the sudden death of Carlos Castellanos in 1903, at the age of just 22, precipitated the outcome in a few days, with the final agreement being completed on 24 March when both presidents signed the merger in which Bilbao FC was dissolved and all of its remaining members and associates were officially absorbed by Athletic, and the side that emerged from the unification was called Athletic Club de Bilbao.

[7][26][28] Since the figure of coach as we know it today did not exist at the time, Astorquia felt obliged to take a step forward and gather the players around him in the Biscayan locker room to give them a harangue.

[1][9] Although little is known about his playing style and personality inside the pitch, the few photographs of the Athletic squads provide good hints without the risk of misunderstanding since in almost all of them, he always appears with the ball either in his hands or buried between his legs, and while his teammates pose smiling, clueless or expectant, waiting for the photographer to activate his camera, Astorquia offers an imposing image with a challenging gaze,[7] and likewise, he was the one with the most imposing and best-kept mustache, with those semicircles that rose from the corner of his lips that gave him an aristocratic look.

[4] Despite being the first great figure of Athletic, the information that has remained about him is very scarce; just a handful of biographical details that are "certainly not enough to do justice to such a fundamental character in the club's history".