The saltpeter mines in Chili were notorious for miserable working conditions and labour exploitation. Striking miners occupied a school in the northern city of Iquique for over a week in December 1907. The number of strikers continued to swell and the army was summoned to end the strike. On 21 December, soldiers stormed the Santa María school and killed the strikers, their wives and children. They were dumped into a clandestine mass grave. The cantata Santa María de Iquique was composed in 1969 by Luis Advis Vitaglich to honour the dead.
On the occasion of the centenary of the massacre in 2007, Chile’s president Michelle Bachelet ordered the excavation of the site. Nearly 2500 bodies were re-interred in a monument. A national day of mourning was decreed for 21 December.