Greeson actually takes well to war, and so does the movie. World War I may have been a plague on mankind, but it was a godsend to film directors. The Mighty is no All Quiet on the Western Front, but Cromwell shoots some impressive overhead tracking shots of soldiers crossing No Man's Land. The war is a proving ground for both Greeson and Jerry Patterson, a gung-ho but "nervous" young lieutenant who envies Greeson's strength and courage but despises his attitude. Greeson gets promoted ahead of Patterson, which seems to prove to both men that you have to think the way Greeson thinks -- like a thug -- in order to do what he can do. But Greeson rethinks his assumptions when Patterson overcomes his nervousness and several wounds to take out a German machine-gun nest, at the cost of his own life.
The Mighty seems poised to be a more ambitious film than it actually ends up being. After the Armistice Greeson returns to America and goes to Patterson's home town. One of his old cronies, Dogey Franks (Raymond Hatton), is on board the train and is stunned to see his pal treated as a war hero. Blake is just about as stunned by the impromptu ceremony at the train station, during which he's given the proverbial key to the city. Dogey playfully heckles Greeson during the march through the station, but he also takes the key-to-the-city concept a little too literally, believing that Blake now has an in to all the town's riches. Blake himself is clearly troubled by the honors heaped upon him. Cromwell films the walk through the station with a tracking shot similar to the war scenes, then cuts to a point-of-view shot as Greeson discovers Patterson's sister (Esther Ralston) sitting in a car waiting to convey him to the family home. The director effectively conveys that this is a moment of dread for Greeson without requiring Bancroft to explain it to the audience by emoting.
At this point the film gives in to melodrama. The city fathers convince Greeson to become their chief of police, believing him eminently qualified by virtue of killing Germans to clean up their town. Blake continues to wear his army uniform on his new job, both as a reminder of the real source of his authority and a sign of his ambivalence toward his position. Dogey has drawn Shiv Starkey and the rest of the gang to town in the expectation that Blake will throw it wide open to them. That's Blake's idea also, after first cleaning up the native criminal element to establish his bona fides. But as Blake falls in love with Louise Patterson, he feels more compelled to live up to the image her brother created in his letters to her. It sounds like Jerry built him up as a total hero, though the cynical attitude toward war Blake expresses to her might bely that. The war was just a big gang fight to Greeson, but Louise shares what we assume was Jerry's belief that something more was at stake. Right or wrong, won't someone always fight for his gang? Aren't you a traitor if you go against the gang? Louise answers by citing not Benedict Arnold but George Washington. He was a traitor to Great Britain, but for the right cause. The gears in Blake's head have already been turning but this conversation accelerates them.
In the end it's not so different from the western archetype of the fugitive outlaw who becomes sheriff in a town where the people don't know him and ends up driving off or shooting down his erstwhile outlaw buddies. Subtler points about Blake Greeson's readjustment are lost amid the cliches, while the dialogue gets corny in a way that weighs down the actors. Bancroft is loose and natural in the early scenes, but turns stiff and ponderous in heroic mode, while seeing Warner Oland as a gangster makes it a good thing he found work on the other side of the law. The Mighty starts strong but sputters to its finish. It may have been an omen for Bancroft's career as a leading man, which hadn't long to go.