In Ernest Hemingway's A Farewell to Arms, Italy is central to the story of protagonist, American Lieutenant Frederic Henry, who is fighting with the Italians against the Austrians (and the Germans). Catherine Barkley, who Frederic falls in love with, is surprised to find an American fighting for and with the Italians.
Over the course of time, Frederic is injured and sent to the hospital. He receives an operation to repair his injuries, and while he recuperates, Catherine is reassigned to his hospital to be with him. This begins a time of great happiness for the pair. They spend the days and nights together. Eventually, Frederic returns to the front, but he finds that the war has changed a great deal. The morale of the Italians as plummeted as the Austrians have been reinforced with German troops.
During this time in the war, Frederic's experiences are much different. As he and other men try to deliver medical supplies, they are stopped by crowds and traffic. They try to make it on back roads. This attempt is also unsuccessful; of the original six men, soon only two of them are left. They witness soldier running away from the front amid mayhem; they see that...
...the retreat column has degenerated into a frantic mob.
Soldiers are leaving weapons behind, men of higher rank are removing any insignia from their uniforms that might identify them as officers. At the end of the bridge, however, the Italian military police are waiting to stop and shoot those trying to desert. Frederic is taken and tied to a tree, but gets loose and jumps into the river. It is here that Frederic becomes a deserter. The war really does not mean anything to him: he is not fighting because he believes in a greater good. However, as a deserter, if Frederic remains in Italy, he can be arrested. Ultimately, he and Catherine will travel to Switzerland which is neutral territory.
This war was the most advanced in terms of military weaponry that the world had ever seen, which is why it was called the "Great War." Wilfred Owen's poetry concerning this war brings images of chemical warfare (the use of poisonous gas), gas masks, living and dying in trenches, the rats, the gore—the general inhumanity of war, and a public's lack of awareness of how horrible it really was. (Owen lost his life in that war.) This "conflict" destroyed the lives of many of the men who survived. The war lasted four years and cost millions of dollars.
In terms of Italy's place in the Great War:
The role of Italy in World War I was as decoy.
The Italians would normally have supported the Austria-Germany side, but Italy had been promised land, and the Allied forces promised to fulfill this agreement.
...Italy's ill-equipped army was to attempt to divert the...Austrians from helping the Germans in France.
In 1916, the Italians lost 500,000 men—in that one year alone, and it is easy to understand Hemingway's description of the mass desertion when so many men were dying. (This was the year Frederic deserted.) Ironically, all was not lost for the Italian army which rallied against the Austrians, and ultimately was rewarded for helping the Allies.
As Italy was only in the war in a secondary capacity (though the body count seems to contradict this), it seems also that Frederic was also in the war in much the same way. He was not dedicated to the Italian cause. At one point he finally realizes that he has had enough, has come close to death too many times, and has risked too much.