Ybarnegaray had undertaken French Resistance activities, assisting escapees in crossing the Pyrenees, for which he was arrested in 1943, and detained in Plansee in the state of Tyrol.
Ybarnegaray je poduzeo aktivnosti u pokretu otpora-pomagao je bjeguncima u prelasku Pireneja, zbog čega je uhićen 1943. godine, i zatočen u Plansee u Tirolu.