Final answer:
The line 'Bent double, like old beggars under sacks' from the poem 'Dulce et Decorum Est' employs a simile, comparing soldiers to old beggars to depict the exhaustion and harsh conditions of war.
Step-by-step explanation:
In the poem 'Dulce et Decorum Est,' the literary technique used in the line 'Bent double, like old beggars under sacks' is a simile. This technique involves a comparison between two distinctly different things using the words 'like' or 'as.' In this case, the soldiers are compared to 'old beggars' to emphasize their exhaustion and the dire conditions they are enduring. This simile creates a vivid image in the reader's mind and conveys the harsh reality of war, contrasting with the notion that dying for one's country is sweet and proper.