Star Wars: Episode 8 director Rian Johnson has revealed a list of films he encouraged his cast and crew to watch before shooting began on the movie.

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1. Twelve O'Clock High (1949)

General Leia.

2. The Bridge on the River Kwai (1957)

Rey and Kylo dueling at the end of The Force Awakens.

3. Three Outlaw Samurai (1964)

Kylo Ren answers to Snoke.

4. Letter Never Sent (1960)

Finn and Rey in The Force Awakens.

5. Gunga Din (1939)

The Knights of Ren.

6. Sahara (1943)

Rey's offer to Luke Skywalker.

They're films about war, leadership, survival, fragile alliances, muddled perspectives, and the notion of redemption through betrayal. Mmmm...Below is a little more about each film and how they might be shaping the next installment in the core Star Wars saga.Brigadier General Frank Savage (Gregory Peck) takes control of the 918th squadron, a demoralised US air force unit tasked with daylight bombing of German targets. These daytime raids had much higher rates of success, but were also much more dangerous for the men undertaking the missions.At first, the men hate Savage, handing in transfer requests, but eventually he wins them around, improving mission success rates and leading them to victory.Johnson said that of all the movies listed, Twelve O'Clock High was the one that influenced Episode 8 the most.Interestingly, for a long time the movie was required viewing at a variety of US service training academies, where it was shown as a example of Situational Leadership Theory. That model believes there's no single best style of leadership, and proposes the best leaders are those who adapt their leadership to the group they are attempting to lead, and even participate themselves.So who's Episode 8's Frank Savage, the charismatic but tough leader?It's almost certainly misleading to look for a single, direct analogue, since both sides of the fight will have to deal with dejected armies following the enormous casualties suffered on both sides during The Force Awakens' final act. Maybe Episode 8 is the story of which character can emerge as the most effective leader: Leia or Snoke? Rey or Ren?A British colonel agrees to build a bridge for his captors, while oblivious to a plan by the Allies to destroy it.The Bridge on the River Kwai is celebrated for its muddy motives and the twisting of perspective. Towards the end of the movie, the British colonel Nicholson (played by Alec Guinness) appears ready to thwart the plan to destroy the bridge he's built for his cruel captors. It's a complex finale, serving as a statement on the madness of war. Good and evil become less distinct, and the 'good' are forced into doing things for their enemies, and as a consequence they're no longer capable of making clear decisions.The film is also noted for the central relationship between Nicholson and Saito, a season British soldier and a Japanese colonel respectively. They're an even match for each other, and eventually share a vision for the completion of the bridge.What if Episode 8 creates uneasy alliances between some of its most opposed characters? Could Leia work with her son Kylo Ren to take down Snoke? Who knows, but the notion of 'good' and 'bad' working together and getting morally lost is really interesting.A wandering ronin becomes tangled with two other samurai who are hired to kill a band of peasants who have kidnapped the daughter of a corrupt magistrate.Critic Bilge Ebiri saw in the movie a "depiction of the loss of honor through blind loyalty (and its liberating opposite, the regaining of honor by betrayal)".Star Wars has a long history of taking cues from Samurai movies (A New Hope was partly-influenced by Lucas' love of Kurosawa), and it's easy to see how these themes could tally with the end of The Force Awakens: Will Kylo Ren realise the consequences of following Snoke blindly? Will he seek redemption through betrayal?Three geologists and their guide head deep into the forest of central Siberia. After almost starving to death, they find a stash of diamonds. Before they can return, they are trapped by a forest fire that cuts them off. They must fight to survive.Letter Never Sent is a drama about isolation, survival, and madness. I'm wondering if it's in this list for a similar reason to Sahara below. Will some of our heroes, maybe even villains, find themselves stranded with the odds stacked against them?Buried within this survival drama is a love triangle, which threatens to destabilise the group as they try to survive. Perhaps, the budding romance between Rey and Finn will threaten to undermine the Resistance as it challenges the First Order.In 19th century India, three British soldiers and a local water carrier attempt to stop a secret mass revival of the murderous Thuggee cult before it can rampage across the land.There's a definite parallel to draw between Snoke, Kylo, and the Knights of Ren and Gunga Din's cultists. Snoke and Ren are trying to revive a lost sect who revere the dark side of the force.Interestingly, during the movie's finale, the cult leader kills himself in order to galvanise his fanatics and motivate them against the British forces. Ultimately they don't succeed, but it provides the movie with a memorable finale. Will Snoke make a similar sacrifice in order to harden his forces against the Light Side of the Force?Gunga Din is a tale about a military force taking on a power it doesn't quite understand and one that it perceives as cruel and barbaric. Recent work by historians has complicated this view, arguing that the Thug cult in the 19th-century was mainly a product of colonial prejudice.I wonder if this is the aspect of Gunga Din that's really caught Johnson's imagination, and he'll do more to communicate the power and lure of the Dark Side – as well as its origin and teachings – when we see Ren reunite with Snoke to complete his training.The crew of a tank, attached to the British Army, and commanded by US Army Sergeant Joe Gunn, becomes separated from its unit during a retreat from the German forces.The unit travels across the Libyan Desert to rejoin its command. Along the way its picks up an international crew of stragglers. The movie follows them on an arduous journey across a hostile landscape. Eventually they reach a well but it's almost entirely dry. German forces arrive, also in desperate need of water. What follows is a battle of wits, as Gunn tries to bluff the German forces into thinking there's water in the well.The set-up is very Star Wars: a small rag-tag group of soldiers, drawn from very different backgrounds, unite to defeat a mightier force through cunning and collective determination.But maybe there's something specific about both sides competing for the same precious resource. Could Rey be what the two sides are competing for in Episode 8? Or the next generation of Jedi?The Force Awakens showed us a glimpse of her power. If properly trained by Luke, it's feasible she could alone determined the outcome of a future war.Star Wars: Episode 8 is scheduled for release on December 15, 2017.

Daniel is IGN's UK Managing Editor. He sometimes writes about movies, too. You can be part of the world's most embarrassing cult by following him on IGN and Twitter