The Huguenot invasion of the Tena valley Historical milestone · Biescas, Alto Gállego, Huesca Image of Biescas, not of the place itself. French Huguenot troops crossed the frontier in 1592, entered the valley and sacked Biescas. The episode decided Philip II to fortify the pass with the fort of Santa Elena, designed by the engineer Tiburcio Spannocchi. 1592 Photo: Willtron (CC BY-SA 3.0) What to see and do in Biescas