In The Islamic Revolution in the West, originally published in 1969 as Les arabes n'ont jamais invahi l'Espagne (Arabs Never Invaded Spain) and subsequently published in Spain in 1974, Olagüe defended various aspects of the theories of Américo Castro. Olagüe argued that it was impossible for Arabs to have invaded Hispania in 711, considering that they had not yet established their dominance over the neighboring part of North Africa. Instead, Olagüe held that the events of 711 could be explained as skirmishes involving allied North African troops within the context of a civil war pitting Catholic Goths led by Roderic against Goths adhering to some form of Arianism and a largely nontrinitarian Spanish population, including Nestorians, Gnostics, and Manichaeans.