There are two meanings to the line, “Men marched asleep.” In the poem. The first one is more of a literal interpretation of the line. The men have been in battle a long time. They are tired but still marching even though they have “lost their boots” and are limping on bloody feet. Owen uses verbs and phrases such as “trudging” and “drunk with fatigue” to get across the images that the soldiers are basically just dead men walking. They move out of duty and necessity, as if asleep with no conscious idea of what they are doing.
The other meaning to the line can be analyzed by understanding the title of the poem, “Dulce et Decorum Est”. Translated, the title means, “It is sweet and right.” At the end of the poem, Owen writes, “Dulce et decorum est pro patria mori” which means, “It is sweet and right to die for your country.” This poem is an example of an anti-war poem and written about WWI about a horrific war of trench warfare with new weapons like mustard gas, tanks, and machine guns. Many soldiers sign up to go to war because of patriotic feelings for their country. It is a great honor to fight for your country. Unfortunately, the realities of war do not match the view of what war is really like. The men are “asleep” to the conditions and situations of war; they don’t understand the loss and destruction they face. They are “asleep” and ignorant of the horrors they will experience when they sign up to be soldiers.
It is during WWI that the term “shell shock” was coined. Today it is called Post Traumatic Stress Disorder and really chronicles the psychological destruction of war that Owen describes in the poem.