I am reminded for the memorable line from John Steinbeck's "The Moon is Down" -- which fictionalized the German occupation of Norway; the invading army takes over a coastal town after a brief, decisive battle, then settles in to administer it and try to make peace with the locals. Instead, the invaders who are portrayed with a fair amount of understanding if not sympathy, find themselves slowly losing their grip as townspeople launch increasingly sophisticated insurgency attacks. Toward the end, one of the invading officers says a line which becomes a theme of the novel: "The flies have conquered the flypaper."