Bilbao fell into the hands of Francoist troops. The engineer Alejandro Goicoechea who designed the Iron Wall, the drawings in hand, changed sides and, for this betrayal, the Franco attacks were carried out from the weakest point that had not ended. 200,000 people fled to Santander by plane bombings. Hundreds of people were shot in the city and 30 prisoners were executed by garrotes. Thousands were imprisoned for being nationalists and many were sent to battalions of forced works. The new mayor of Bilbao, the Falangist José María de Areilza, participated actively in the repression.