Graduated in law in 1914, Lussu took part in the campaigns for the entry of Italy to WWI. A complementary officer of the Brigata Sassari (the famous Sassari's infantry Brigade of italian army), in 1916 he was in Asiago where the brigade had been suddenly been moved, with the duty of opposing the Austrians' descent to Verona. The first victorious resistance was followed by a counter attack (mainly on Monte Zebio and Castelgomberto) that lasted until July 1917. This kind of war was somehow very simple and very cruel, a trench war sometimes fought using knives and bayonets rather than firearms, and was ended with a heavy cost in human lives by the brigade.
By this experience Lussu derived the masterpiece by which he is mostly known: "Un anno sull'Altipiano" (A year on the plateau), written in 1938, in which he memorably described the life of soldiers during WWI and in trench war, underlining for the first time in Italian literature the irrationalities, the lack of sense of war and of military life and discipline.
Gifted with a chill rationalism, Lussu could icily demonstrate how distant the real life of soldiers in war could be from common thoughts, how vainly cruel the military discipline was toward poor illiterate peasants, how little respect the authorities (generals and other higher officers) deserved. In a notable passage, he described the silent terror of the moments preceding an attack, the abandon of the "safe" protective trench for a projection into an external unknown, risky, undefined world: All the machine-guns are waiting for us.
It has been noted that this work is constantly gaining modernity, and its content is becoming constantly more understandable as a common consideration of war evolves toward the direction of general condemnation. Effectively, many concepts contained in the book found a posthumous confirmation in more known cultural movements, political ideologies and popular feelings of later times, after WWII and later conflicts.
Many political meanings have been added to this work, sometimes with roughly instrumental purposes, but it is essentially written in the form of a reportage, quite in a journalistic style or half way to a familiar report, and the reflections that it contains or suggests, are perhaps more at a moral or philosophical level. Previously an "interventista" (favorable to entrance in war) and a revolutionary (in Giustizia e LibertÓ), Lussu practically somehow seemed to repent, soberly describing what war effectively was in its most cruel moments. A social theme regarding how poorer classes were "used" for bellicose purposes, is to be found however in the pages of this book, and some critics find in this element the creation of a "Sardinian Question", and endless discussion about the respect of the island by Italy.
At the end of the war, effectively, in 1919 together with Camillo Bellieni he had organized the foundation of Partito Sardo d'Azione, the nationalistic party of Sardinian people. The party was given a formal personality in 1921, with a subsidiary goal of opposing the increasing power of the fascist movement. Lussu was elected to the Italian parliament in 1921 and in 1924 was among those deputies who "retired on Aventine hill" after the murder of Giacomo Matteotti.
His anti-Fascist position was one of the most radical and sharp of all the Fascist era. Lussu was personally and physically attacked and injured by unknown aggressors several times. In 1926, during one of these attacks (notably, the same day that Mussolini suffered an attack in Bologna), Lussu shot one of the squadristi, so he was arrested and tried; he was discharged because his act was recognised as a legitimate defense, but he was soon condemned by an administrative Fascist commission to 5 years of confinement in the far island of Lipari, near Sicily.
In 1929 Lussu escaped from his confinement and reached Paris, where he wrote another book on his experiences in the decade (La catena - the chain). Together with Gaetano Salvemini and Carlo Rosselli he then gave life to "Giustizia e LibertÓ" (Justice and Freedom), an anti-Fascist movement that proposed revolutionary methods to replace the Regime. In hiding he was known in English as "Mister Mills" . In 1936 in Switzerland he wrote a book on the theory of insurrection.
He took part into the civil war in Spain and was again in Italy after the armistice of 1943, joined the Resistenza and became the secretary of Partito d'Azione (not the Sardinian one, despite the assonance) for southern Italy. He became the absolute leader of the leftist wing of this party and later merged it with the Italian Socialist Party.
After the war he was a minister for aid in the government of Ferruccio Parri and later a minor minister in Alcide De Gasperi's government.
In 1964 he separated from Socialist party creating the PSIUP (Italian Socialist Party of Proletarian Unity). His polemic contrast with the new political line of Partito Sardo d'Azione became deeper and Lussu completely lost contact with the island for whose prestige, respect and spirituality he himself had created a party. He died in Rome in 1975, now also ideally far from his land.
The alteration of Lussu's opinion of war caused his reputation to be widely discussed: first an interventista, then the author of a manual for revolution, soon after the author of a quite pacifist book, then again a revolutionary and a volunteer in Spain, Lussu's consistency was doubted and a political debate often invaded an ordinary cultural critic evaluation of his figure. The book in itself remains as a masterpiece, and is usually evaluated in isolation, but the general view of the man was in most cases moved to a political level, also given the relevance of political activity in his whole life.
Lussu married Joyce Salvatori, now better known as Joyce Lussu, a poet from a noble family of Marches, an Italian notable intellectual whose early works, due to her international education, were translated into Italian (by Benedetto Croce).