The United Nations chose today because it's the anniversary of the assassination of Patricia, Marie and Minerva Mirabal in 1960 in the Dominican Republic. (Photo taken from this site.) The sisters, known as the "Unforgettable Butterflies," became a symbol of the crisis of violence against women in Latin America. November 25th was the date chosen to commemorate their lives and promote global recognition of gender violence, and has been observed in Latin America since the 1980s.For more information, go to the UNIFEM site.