How does the author use foreshadowing in The Pushcart War?

The photo Marvin Seeley takes of Morris in the pickle barrel provides proof later in the war of exactly how the war began. This develops the plot by providing the reader with a substance of proof that can be looked at and studied. This chapter also foreshadows later events in the war, since the writer announces in this chapter that the picture will be published later in the war. What affect this publication will have on the war is a question. the reader will see answered later in the novel.