On 22 July 1915, after Italy's entrance into the First World War, he was assigned to the 142nd Infantry Regiment as commander of machine gun platoon, and in the same year he was awarded a Silver Medal of Military Valour after being wounded in combat on the Karst Plateau.

After being assigned to the General Staff, he was promoted to colonel on 16 August 1933 and given command of the Cavalleggeri Guide Regiment in Parma, which he held until 10 November 1935.

On 22 January 1942 he was sent to Libya with his division, participating in the Axis advance into Egypt and the subsequent fighting near El Alamein (with an interruption between 8 July and 20 September, when he was attached to Delease).

After the destruction of his division in the second battle of El Alamein, on 4 November 1942, Bitossi became interim commander of the XX Corps in Tunisia, until his repatriation on 1 March 1943.

[1][2][3][4] In April he wrote Frammenti di una esperienza decennale di guerra motorizzata 1933-1943 ("Fragments of a decennial experience of motorized war 1933-1943"), an important report addressed to crown prince Umberto and Generals Ambrosio, Roatta, Sartoris, Cadorna and Sorice, to report on the conditions in which his division had operated in the North African campaign.