[1][2][3][4][5] During the Fascist regime, Lessona was among the protagonists of Italian colonial policy; after serving as undersecretary at the Ministry of Colonies from 1929 to 1936 (acting as de facto minister, with Mussolini being the titular minister), after the outbreak of the Second Italo-Ethiopian War he played an important part in having General Emilio De Bono removed from the command of the northern front and in entrusting this command to Marshal of Italy Pietro Badoglio at the end of 1935.

A few months later he discovered an evident embezzlement, which directly involved the former governor of Eritrea Emilio De Bono, and ordered the works contract to be rewritten.

The question was brought to the attention of Mussolini, with whom De Bono had much greater influence than Lessona, and the Duce began to look critically at his minister, asking to supervise his work.

Within a few months, a long series of negative reports accumulated on Lessona ranging from corruption, to the casual assignment of public offices, and above all to the suspicion that he was building a personal domain of his own in East Africa.

Ethiopia had appealed to a clause of the Peace Treaty, which indicated an uninterrupted state of war between it and Italy since 3 October 1935; subsequently, in November 1948, the Ethiopian government asked for the surrender of the accused to put them on trial.

However, Italy managed to obtain from the Allies the renunciation of the application of these clauses, committing to directly provide for the judgment of all the alleged criminals, identified by the UN Commission.