What is the significance of the song by Waris Shah?

At the start of the Jamadar Harnam Singh on night watch. At two o'clock, he wakes Ganda Singh to take over the watch and lies down to sing a romantic song about a pair of shoes with stars on them. Banta Singh joins in with a song about love and tragedy (Waris Shah). This is significant because it illustrates that sadness creeping over the soldiers, as they are reminded that life should be about love rather than about war.