In the poem "Dulce Et Decorum Est," Wilfred Owen refers to a line from Horace when he says, "How fitting it is to die for one's country." However, Owen prefaces this line with the words "The old Lie" because he wants to challenge the idea that it is fitting to die for one's country. Throughout the poem, the speaker details the horrors and hardships that soldiers must face on the battlefield, including poisonous gas and fatigue. The fighting kills any hopes and dreams that the soldiers may have had in their civilian lives.
In the novel All Quiet on the Western Front, Remarque makes similar comments about the nature of war. The novel's protagonist Paul Baumer says that the young soldiers' lives have become "a wasteland" because they do not understand why they are fighting yet they have lost all their hopes, dreams, and future aspirations because they have become so degraded by the war. In Chapter 9 of the novel, Paul is trapped in a shellhole with a French soldier and he instantly attacks him because he sees the Frenchman as the enemy. However, Paul then realizes that this man is simply a man just like himself with a family and probably his own dreams. Paul then regrets his actions and prays that the soldier lives. When the man dies, Paul is scarred.
So, the novel and the poem both espouse similar themes--that it is NOT fitting to die for one's country and that this extreme sense of patriotism and nationalism goes against our humanity.