Sergio Leone had a very small (though influential) body of work, but there are a few films of his that tend to be overlooked. Many forget his (uncredited) directorial debut in The Last Days of Pompeii as well as the feature that followed: The Colossus of Rhodes. Those two were followed by Leone taking a job working on a cheap spaghetti western to make up for the studio's previous failure, which would become A Fistful of Dollars and which in turn would become such a success that Leone was launched to fame and given incresingly larger budgets with which to make For a Few Dollars More and The Good, the Bad, and the Ugly. He then went on to direct Once Upon a Time in the West and Once Upon a Time in America.
There is one movie I left out of that description. It is an easy one to forget of Leone's known in English by one of two different titles: Duck, You Sucker or A Fistful of Dynamite (even DVD copies tend to print both titles). If you've been to my YouTube Channel you may have heard of this film, in which case I'd imagine the first thing you'd think of is John Mallory's relentless determination to blow up Hitler for no readily apparent reason.
But what of the original movie? The parodies are hilarious but let's look at the film as Leone originally intended it. Rod Steiger plays the role of Juan Miranda: a Mexican bandit trying to provide for his family who is really only as rough as he is because it's the only way to survive.
Both men cross paths in the midst of the Mexican revolution, and team up to rob a bank. However, that plan soon takes an unexpected turn and Juan finds himself forced to join the Mexican rebels. Most of the movie centers around the relationship between these two characters: a sort of uneasy friendship that develops between them (though they're not above double crossing each other).
When you get down to it, the whole movie is really about deconstructing the concept of a "revolution". The Mexican revolution provides a backdrop, but at its core it's really about the ethics of revolutions in general. Revolutions are violent and ultimately never justified. Even if the people conducting the revolution have noble intentions, thousands of people will die for nothing, and ultimately the rebels seem no better than the oppressive government they are fighting against. There's even a really good scene where Juan pretty much sums up the whole theme of the movie:
There's no doubt the movie can be pretty disturbing at times, especially in the second half when we really start to see the darker side of revolutions. It does take a strong stomach to sit through the scenes of mass executions by firing squad.
From a technical standpoint, Duck, You Sucker! is also a pretty well-done movie. Coburn and Steiger do play well off of each other, the action scenes are appropriately tense, and the darker scenes can get pretty emotional. As you might expect from a Sergio Leone film, we also get a great soundtrack by Ennio Morricone, some very interesting ways to utilize sound to different effects, and plenty of great landscapes. It is definitely an underrated film of his, and one worth checking out, so don't duck, you sucker, or you might miss it!