During 1976, which prison had Spain's largest prison break since the Spanish civil war?

The Segovia prison break occurred in Segovia, Spain on 5 April 1976 when 29 political prisoners escaped from Segovia prison. This was the largest prison break in Spain since the Spanish Civil War. The prisoners escaped by means of tunnels they had excavated and then through the prison's drainage system. Hidden in a truck, they fled in the direction of the French border. Before reaching the border, their escape plans broke down and they found themselves stranded and lost in woodland in Navarre.

Most of the prisoners were recaptured after a confrontation with the Civil Guards in Espinal, during which one of the prisoners was shot dead. The remaining four escapees managed to cross the French border and were detained by the French government, but escaped once again. In 1977, the Spanish authorities declared a general amnesty, after which the escapees were freed or could return to Spain.