O’Duffys legacy is defined by being the leading figure in the fascist movement in Ireland in the 1930s, and for bringing 700 supporters to Spain in 1936 to fight on the side of General Franco as he sought to overthrow the Spanish republic and establish a dictatorship.

Even modern Irish musicians have weighed in on the topic with Christy Moore pouring scorn on this part of O’Duffys life in the song Viva la Qunita Brigada singing And the Bishops Blessed the Blueshirts Down in Galway as they Sailed Beneath the Swastika to Spain.