In World War I, Messe was a battalion and Arditi (shock troops) unit commander, distinguishing himself during a successful counterattack in June 1918 on Mount Grappa. In 1920, he fought in Albania as an assault unit commander. Promoted to colonel, he was assigned to the War Ministry, and from 1935, he commanded the Celere Brigade (a mobile unit). He took part in the 1935–1936 Ethiopian Campaign as a brigadier general and deputy commander of the Cosseria Division, and on his return to Italy, he was named deputy commander of mobile troops. In April 1938, Messe took command of the 3rd Celere Division. He was then sent to Albania as deputy commander of occupation troops. On 21 December 1940, following Italy's invasion of Greece, Messe was assigned command of the Special Army Corps, formed to check the Greek counteroffensive.
In July 1941, Messe was promoted to temporary lieutenant general and assigned to the Soviet Union as commander of the Corpo di Spedizione in Russia (CSIR, Expeditionary Corps in Russia). In July 1942, Messe's unit was renamed the XXXV Corps, and he continued as its commander. Promoted to full general on 31 January 1943, he was assigned to Tunisia as commander of the First Italian Army, which included the Italian units formerly under Field Marshal Erwin Rommel's command. On 8 May 1943, following a number of defensive battles, First Army surrendered to the Allies. Messe had been promoted to marshal a few days before the surrender. Repatriated on his demand in November 1943, he was appointed chief of staff of the new Italian army on the Allied side. He held this post until 1945. Messe wrote two books of memoirs. Probably the best Italian army senior commander of the war, he was widely respected by his own troops and his German allies.
In 1953, Messe entered the Italian Parliament as a senator in the Christian Democratic Party. Two years later, he founded and became the head of the Unione Combattenti d'Italia (UCI, Italian Veterans Association), which had a strong monarchist bent. In 1957, he was elected to Parliament as a member of the Monarchical Party, and in 1963, he was elected to the same body as a representative of the Liberal Party. Messe died in Rome on 18 December 1968.
Bovio, Oreste. Storia dell'esercito italiano (1961–1988). Rome: Ussme, 1990.; Cannistraro, Philip. Historical Dictionary of Fascist Italy. Westport, CT: Greenwood, 1982.; Messe, Giovanni. La mia armata in Tunisia. Milan, Italy: Rizzai, 1946.; Messe, Giovanni. La guerra al fronte russo. Milan, Italy: Rizzai. 1947.