European pastoral imagery
Life is a state of true community in this small European town. It's a slice of heaven, until the Nazis come with their tanks and soldiers to occupy there. The imagery of the town is seductive to the lonesome, romantic Captain Tonder, as it would be—the town is obviously very scenic from Steinbeck's idyllic prose. The pastoral imagery has the overtones of moral goodness and ethical living.
Industrial imagery
The novel features the futuristic, nearly unthinkable technology of the German army, along with their machine-like approach to humanity. The Nazi army is famously willing to commit atrocities and crimes of war, but part of that is depicted through their imagery, because the organic, timeless feel of the village is interrupted by machines, machine guns, and men who act like a machine, coldly assassinating innocent people and dominating innocent towns.
The imagery of power
Many of the characters in this novel are associated closely with power. For instance, the hero of the novel is arguably Mayor Orden who resisted the Nazi pressure to comply. He also teaches the town about their own sovereignty as individuals, something the Nazi's don't appreciate. Their version of power is clearly bureaucratic and cut throat, and their leaders often compete for promotions instead of sacrificing for others.
Pictures of death
The imagery of death is an unfortunate companion to Nazi imagery. The imagery of death is evident in German weapons, in the skulls in their decoration, the dead and dying of World War II, the prospect of death for Mayor Orden, Alex, Molly, and the Nazis who are tricked and killed by the townspeople. The reality of death disrupts order, as Orden notices in his speeches. Because the Nazis have brought death, he feels the townspeople should do what nature tells them to do, which is to fight for their home. At what cost? At the risk of certain death.
