How does the author use foreshadowing in Sergeant Musgrave's Dance?

Act I, Scene I, is the beginning of a literal and spiritual journey for Musgrave and his men. The literal journey, as the Bargee says, takes them into the bleak north of England. The spiritual journey takes them into their own bleak souls, where they encounter one of the darkest of human emotions, guilt. What awaits them at the end of both journeys is foreshadowed by the references to the Gatling gun (a machine gun with multiple barrels), to the "he" in the box (eventually revealed to be a dead comrade), to desertion as sung about in Sparky's song and to duty as referred to in Musgrave's speech.