"Dulce et Decorum Est" by Wilfred Owen is one of the most well known poems of World War I and is recognized for its ability to portray an urgent scene from the battlefields whilst also showing a clear disillusionment on the part of the narrator with regard to suffering and war.
The title, repeated in the final lines of the poem, comes from a Latin saying known through an ode by Horace. It is normally translated as “It is sweet and right." The phrase finishes with “pro patria mori” which means “to die for your country.” This was a popular saying during the war, and the glorification of the war, along with an insistence on the heroism of soldiers, was common throughout the war years and afterward.
The soldier here, the narrator of the poem, may once have believed those words, but being exposed to the horrors of war has changed his opinion. He graphically points out the distress and horrible conditions in which the soldiers live and fight, in lines such as “Knock-kneed, coughing like hags, we cursed through sludge.” He witnesses the suffering of a fellow soldier during a gas attack, an image that will haunt him:
In all my dreams before my helpless sight,
He plunges at me, guttering, choking, drowning.
He can find no peace in this suffering or death, no sense that it is worth it; as such, it represents a shift in his understanding of the world, and his soul is left stranded. The narrator of the poem addresses the reader to explain that if they too had witnessed such a horrible sight, and its aftermath, they would not continue to encourage young men to go to war or act as if it is heroic to die or be injured in battle.
My friend, you would not tell with such high zest.
To children ardent for some desperate glory
The old Lie: Dulce et decorum est
Pro patria mori.
His personal transformation can be understood as a shift from being proud to go off to war with the troops to being disgusted at the reality that awaits those enthusiastic troops. He is completely disillusioned and horrified by the realities of war. This has a wider implication in that it is not just a personal transformation, but a call to the reader to join him in condemning the brutalities of war and challenging assumptions about patriotism and the purposes of war in general.