Why is the narrator left in despair at the end of the story The Old Man at the Bridge?

The narrator is left in a state of despair at the end of the story because he is worried about the old man but is unable to offer him any help. The narrator is a scout of sorts for the camp of soldiers fighting against the fascists. His work involves exploring various places beyond the bridge to check on the movement of the advancing enemy. It is while doing this that he observes the old man sitting by the roadside even as everybody else hurries to cross the bridge to move to safer places.
The old man is seventy-six years old and does not have any close relatives, except for “two goats, a cat, and four pairs of pigeons,” which he had to leave behind in his hometown of San Carlos, because of the artillery. He is tired after walking about twelve kilometers and does not have the strength or the desire to walk any further. The narrator urges him to walk on at least until he can get to the trucks further up the road which will hopefully take him to Barcelona. However, the old man is too weak to walk any further. He tries to stand up, “sways from side to side and then sits down backwards in the dust.” The whole scene paints a picture of sad hopelessness in the reader’s mind. The narrator is saddened by the plight of this old man who is surely a victim of a war that he does not understand, for, as he states “he is without politics.”