According to the narrator, the crew of the Indomitable treated the spar from which Billy was hanged as a monument. A piece of it was as valuable to them as a piece of the cross on which Christ was crucified.
The crew's camaraderie is so strong that they treat Billy as a kind of Christ figure, largely based on his appearance and the story of his death. The comparison also suggests that Billy did not deserve to die and was unjustly executed.
The sailors remembered Billy fondly and memorialized him in a song that became a sailors' ballad. The narrator gives the words to the ballad, entitled "Billy in the Darbies," which narrates the final moments of Billy's life sympathetically and tragically.
In contrast to the naval chronicle, the sailors memorialize their comrade in a ballad. While such songs do not have a reputation for veracity, "Billy in the Darbies" is in some ways truer to the reality of Billy's death than the official report in the chronicle.