He was one of the key figures behind Italy's anti-partisan policies in Libya, such as the use of poison gas and concentration camps, which resulted in the deaths of tens of thousands of civilians and have been described as genocidal.

De Bono then fought in the First World War in which he distinguished himself against Austria-Hungary on the Karst Plateau in 1915 (as Colonel in the Bersaglieri corps), in the capture of Gorizia in 1916 (as commander of the "Trapani" Infantry Brigade), in the Second Battle of the Piave River in June 1918 and in the battle of Monte Grappa in October 1918 (as commander of the IX Army Corps).

De Bono was one of the key figures behind Italy's anti-partisan policies in Libya, such as poison gas and concentration camps, which resulted in the deaths of tens of thousands of civilians and have been described as genocidal.

The plan outlined a traditional mode of penetration: a relatively-small force would move gradually southward from Eritrea, establish strong bases and then advance against increasingly weak and disorganised opponents.

Increasing world pressure on Mussolini brought a need for fast glittering victories, and he was not prepared to hear of obstacles or delays.

[9] On 16 November, De Bono was promoted to Marshal of Italy (Maresciallo d'Italia), but Mussolini grew ever more impatient with the invasion's slow progress.

In 1940, De Bono commanded a southern defense corps headquartered in Sicily and was opposed to the Italian entry into the Second World War; he filed a scathing report about the condition of the troops in Sicily, pointing out that the "mobile battalions" were not mobile at all, and harshly criticizing both the Maritime Artillery Militia and the Anti-Aircraft Defense Militia.

The only person on trial who escaped from capital punishment was Tullio Cianetti, the Minister of Corporations, who was sentenced to 30 years' imprisonment by the RSI judges.

[10] De Bono and the other condemned, tied to chairs as it was in use in Italy, suffered the humiliation of being shot in the back as traitors.

After hearing the sentence, De Bono reportedly remarked "You barely got me; I am seventy-eight", but later complained about being shot in the back, which he considered a stain to his honour as a soldier.

[11][12] Like his maternal grandfather, Emilio was reportedly an atheist, as he stated in his "Memoirs" in 1941: "Atheism is enlightened and rational, based on scientific principles.