Why do the last two lines of "Dulce et Decorum Est" repeat the title?

Wilfred Owen titled his poem after a Latin saying that means "how sweet and fitting it is to die for one's country." The poem was written as a protest to those who recruited young men to serve in World War I by presenting a rosy and unrealistic picture of the life of a soldier. Owen, who served in battle himself, wanted to portray the horrors of trench warfare, not to dissuade men from enlisting, but to make sure everyone, recruits as well as the public, knew the great sacrifice Great Britain was requiring of its soldiers. By beginning and ending the poem with the Latin saying, Owen emphasizes the verbal irony that is central to his poem. Being confronted with the Latin phrase in the title before reading the poem, readers may at first expect that the poem will support the sentiment. When they read of the horrible conditions, the death of the man who doesn't get his mask on in time, and the tormenting nightmares of the man's fellow soldier, readers begin to question the Latin phrase from the title. What Owen describes is anything but "sweet and fitting." At the end of the poem, Owen states clearly that the saying is "the old lie." He then repeats the entire sentence, this time including the part "to die for one's country." The ending brings the poem full circle and emphasizes the contrast between the saying and the reality.