The Fort du Portalet is a fort in the Aspe valley north of the present Spain-France border which guards access to the Col du Somport. It was built by order of Louis Philippe I to guard the border of the Pyrenees. Installed against a cliff overlooking the Gave d'Aspe, it faces the path of Masts. It was begun in 1842 and finished in 1870, replacing an earlier structure a further north. During WWII Léon Blum, Édouard Daladier, Paul Reynaud, Georges Mandel and Maurice Gamelin were interned under the Vichy regime. After the war Philippe Pétain was imprisoned in the fort from 15 August to 16 November 1945.