08 December 1977,
The First Meetings of Women of the Basque Country began at the University of Leioa. For four days they reflected on sexual freedom, patriarchal oppression and the fight against it. There were 3,000 women who marked a milestone in the feminist movement of the Basque Country. There they sang for the first time the song "Standing Women." Since then, the song has spread to different places in the Basque Country.
Source:
Ilargi Bengoetxea Gartzia, feminism of the second wave. Peculiarities and incidence in the Basque Country; First Meeting of Women of the Basque Country in 1977 (University of the Basque Country, Final Degree Work)