His detachment of 800 men was ordered to establish a bridgehead under enemy fire: it managed to do so, but was only left with 23 members at the end of the day.

D'Annunzio told Muti: "You are the expression of Superhuman values, a weightless impetus, a boundless offering, a fistful of incense over the embers, the scent of a pure soul".

He joined the Regia Aeronautica (Italian air force), developing a passion for aircraft – he accepted demotion to lieutenant, according to the practical requirements of the service.

In 1936 he returned to Italy, but left soon after as a volunteer on Francisco Franco's side in the Spanish Civil War, fighting under the pseudonym Gim Valeri.

As a lieutenant colonel, Muti participated during the Italian invasion of France, during the long-range bombing of Haifa and Bahrain,[2] and during the Battle of Britain.

On 25 July, the day of the pro-Allied coup d'état in the Grand Council of Fascism, Muti was in Spain, trying to obtain the radar set of a United States aircraft that had crashed on neutral territory.

The official communiqué stated: Following an investigation into major irregularities in the administration of a state-associated entity, during which the implication of the ex-secretary of the dissolved fascist party, Ettore Muti, has become apparent, the Carabinieri military corps proceeded in Muti's arrest at Fregene, near Fiumicino (then part of the comune of Rome), on the night of 23–24 August.

In the momentary disturbance, he attempted to run away, but, after being shot at and wounded by the Carabinieri, he died.The major irregularities mentioned were never clarified, nor were the identities of shooters in the forest.