A convinced Catholic, and a Mazzinian and democrat by education, he opposed the violence of both the Communists and Fascists, being expelled from the board of L'Azione after Mussolini came to power.

From 1922 to 1927 he was secretary of the Società istriana di archeologia e storia patria, and in 1936 he graduated from the University of Padua with a thesis about Marco Minghetti, published in Gorizia in 1960.

[2] He was put in jail by the Nazis during the 1944 German occupation of Istria, being considered suspicious because of his relations with non-aligned personalities and because of his frankness, but was freed shortly after his incarceration.

However, it was ultimately decided that Istria would be annexed by Yugoslavia, and Craglietto and the Comitato di liberazione nazionale had instead to face the organization of the Istrian–Dalmatian exodus.

[2] Craglietto then moved to Italy, in Gorizia, where he became president of the scientific lyceum Duca degli Abruzzi, holding this post for ten years; meanwhile he continued with his studies, mostly on historical linguistics.