How did Matthew Arnold in his poem 'Dover Beach' portray the real world which we live in?

The use of the first person plural here is somewhat puzzling. Matthew Arnold does not portray the world in which "we" live, as both of us, your instructor, and all possible readers of this response were born long after the poem was written. None of us live in the world of the mid-nineteenth century.

The setting of "Dover Beach" is realistic, in the sense that rather than being set in an imaginary world, such as...

The use of the first person plural here is somewhat puzzling. Matthew Arnold does not portray the world in which "we" live, as both of us, your instructor, and all possible readers of this response were born long after the poem was written. None of us live in the world of the mid-nineteenth century.

The setting of "Dover Beach" is realistic, in the sense that rather than being set in an imaginary world, such as the fantastic quasi-medieval setting of Keats' "La Belle Dame Sans Merci" or the hallucinatory environment of Rossetti's "Goblin Market", "Dover Beach" portrays a situation that could have happened to an average middle class person of the period and geographical location.

In the poem, a man is looking out over the English Channel, seeing the lights of the French coast glimmering in the distance. He describes in some detail the appearance of the cliffs and the sea, descriptions that are quite accurate in such details as the color of the cliffs and the sound of the waves. From Dover, on a clear night, it is possible to see lights on the French coast as the strait is only slightly over two miles wide at this point.

The basic dramatic situation of a man talking to a woman he loves before a voyage is also one within the realm of ordinary experience. In the nineteenth century, British journeys to the Continent would normally start at Dover, as opposed to the twenty-first century in which we are just as likely to start journeys from airports. 

Finally, the metaphor of a place where "ignorant armies clash by night" reflects not only the confusion of actual warfare but also a recollection of the previous wars between France and England.