This movie is based on one of John Steinbeck's lesser-known novels. I have a feeling that Steinbeck wrote the novel for much the same reason that the movie was made: Propaganda in support of the War.
Nunnally Johnson wrote the play for the movie, based on Steinbeck's novel, just as he had written the screenplay for Steinbeck's The Grapes of Wrath (1940). Nunnaly's wife, Dorris Bodon, had an acting role of both of these movies. The movie's director, Irving Pichel, had a small unaccredited role, here, as the Inn Keeper. Natalie Wood made her first screen appearance in this movie and then went on to make her 2nd, 3rd and 4th movie appearances in Irving Pichel-directed movies: Happy Land (1943), Tomorrow Is Forever, (1943), and The Bride Wore Boots (1946).
This movie is not so much star-oriented as it is character–oriented, with great character actors taking on the main roles. Cedric Hardwick plays Col Lanser, the coy and pragmatic Nazi officer who is assigned to take over a small Norwegian mining village for it rich iron mines. After the German victory, the village historian, Dr. Winter (Lee J. Cobb), acerbically jokes with its mayor, Orden (Henry Travers), that the German victory only took 4 hours and the victory was announced before anyone know there was even a battle.
The "victory" takes place as hundreds of German paratroopers are dropped into the small village while its tiny militia is enjoying a picnic and shooting contest in the country. The picnic had been arranged by the local store keeper, George Corell (E.J. Ballantine), with the hope that he will be quickly advanced up the German ranks and sent to Berlin.
When Col Lanser interviews Dr. Winter, the mayor, and his wife, Sarah (Margaret Wycherly), they are outraged by Corell's treachery. When Lanser tells Orden that the miners must work harder to supply iron for Germany, Odren tells him that Germans do not understand the people they conquer--they never have, and they never will. Free people do not take orders from a dictator, they live to be free and their freedom is build around an idea—not an order from a dictator. Just as Odren says, the people of the village are not easily pushed around. It is easier to conquer a country in battle than it is to occupy it by telling its free people what they MUST do to stay alive.
The movie demonstrates this and it also has scenes that demonstrate that soldiers are trained to fight and win territory–not to manage the people they have vanquished. Not only do the Norwegians slow down their work in the mines, they also commit acts of sabotage on those mines, and engage in other acts of resistance against the Germans who occupy them. This only increases as the RAF drops parachuted packets of dynamite to help them with these many "small" acts of resistance such as blowing up bridges and roads and other means of production and distribution of the mined iron that is to be used by Nazis in their war.
In the end, the German soldiers grow tired of being hated by the locals and guarding against their acts of resistance rather than fighting wars. This is demonstrated when one soldier, Lt. Tonder (Peter van Eyck), tries to just enjoy the simple company of one Norwegian woman, Molly Morden (Dorris Bowdon). Though she is lonely and is very hungry— food is being withheld from the families in order to feed the soldiers and iron miners—she remembers that Tonder was responsible for killing her husband. So, she stabs Tonder to death with a pair of scissors then manages to escape to Sweden.
In the end, "the flies conquer the flypaper."
