Duty is one of those words that used to carry great weight but really doesn't anymore. It is still an important concept in military circles, but elsewhere doing something because it's your duty has acquired a negative connotation. "You just say you love me because you think it's your duty." "They just go to church out of a sense of duty."
In the nineteenth century, though, calls to duty were inspirational. Just before the sea battle of Trafalgar, Admiral Nelson sent up signal flags that sent this message to the fleet: "England expects that every man will do his duty." The words electrified not just the sailors, inspiring them to victory over Napoleon, but the English people, who turned the line into a national slogan. William Wordsworth was a Romantic poet with a revolutionary impact, but he wrote an emotional celebration of the concept in his great poem "Ode to Duty."