The Bridge on the River Kwai is David Lean's last film not to succumb to bloat. Despite its grand, Oscar-bait stature, the 1957 epic subtly develops its themes about the irrationality of honor and the hypocrisy of Britain's class system without ever compromising its thrilling war narrative. Whereas Lawrence of Arabia and Doctor Zhivago feel more pictorial than cinematic, The Bridge on the River Kwai carefully builds its psychological tension until it erupts in a blinding flash of sulfur and flame.
At its heart, The Bridge on the River Kwai is a study of human will. In the stuffy British army officer Col. Nicholson (Alec Guinness), Lean creates the perfect embodiment of irrational willpower. Captured by the Japanese in western Thailand, Nicholson leads his men to the labor camp where they'll be forced to work on the construction of a bridge the Japanese need for their railroad. When the Japanese commander, Col. Saito, orders that even the officers must work on the project, Nicholson protests. Under the Geneva Convention, officers are protected from being forced into manual labor. Saito objects and considers gunning down Nicholson and the officers in front of their men. When he relents, due to the presence of too many witnesses, he makes them stand out in the blazing sun the whole day, then places Nicholson in a sweatbox. Surely, this must be a greater physical torment than actually working, but that's beside the point for Nicholson. There is no greater dishonor for the aristocracy, of course, than manual labor!
When Saito finally agrees to let him out, in honor of the anniversary of Japan's victory over Russia in 1905, it's with the agreement that Nicholson will supervise the construction of the new railway bridge that's way behind schedule. In order to prove what he feels is the cultural superiority of the British, Nicholson decides to build the best bridge that his troops are capable of. Of course, this means rendering major aid to the enemy, but that's less important than demonstrating British skill and competency. For him, protocol has become a reflex, a kind of muscle memory. When knocked down by an explosion moments before he himself destroys his beloved bridge, he picks himself up, dazed and uncomprehending, yet still straightens up his uniform, oblivious to the bullets flying around him.
It's a testament to the script that The Bridge on the River Kwai doesn't ever try to explain Nicholson's counter-intuitive motives. Today a character like this would surely fall victim to the kneejerk psychoanalysis inherent in so much of contemporary cinema—think of Daniel Plainview in There Will Be Blood—and his obscure motivation would be explained in easy to comprehend terms.
Neither does Lean find it necessary to underline his film's provocative themes with blaring music to signify dramatic import. The nature sounds Lean relies on instead prove a lot more powerful. When Nicholson is locked in the sweatbox, the incessant screeching of cicadas provides the perfect sonic expression for his sweltering misery—and the indifference of nature to his quest for honor. And during the final sequence, when former POW Shears (William Holden) returns to blow up the bridge, the slowly mounting tension feels all the more palpable without any musical accompaniment. Instead, the sound of Nicholson's footsteps echoing off the wooden planks of the bridge, the subtle rush of the river flowing below, and the percussive rumble of the train in the distance provide a deep, suspenseful awareness of this jungle environment and Shears's critical mission within it.
The Bridge on the River Kwai is an easy film to take for granted, but it's the last time Lean challenged his audience with characters possessing obscure motivations without the window dressing of flat, Freddie Young cinematography and a Maurice Jarre music-box score. With the possible exception of Ryan's Daughter, Lean would never again match this achievement.