Murphy's War is an Eastmancolor 1971 Panavision war film starring Peter O'Toole and Siân Phillips. It was directed by Peter Yates, based on the 1969 novel by Max Catto. The film's cinematographer was Douglas Slocombe.

The film is set in Venezuela during World War II and focuses on a stubborn survivor of a sunken merchant ship who is consumed in his quest for revenge and retribution against the Nazi German submarine that sank his ship and slaughtered the survivors.

In the closing days of World War II, Irish crewman Murphy is the sole survivor of the crew of merchant ship Mount Kyle, which had been sunk by a Nazi German U-boat and the survivors machine-gunned in the water. Murphy reaches the shore and finds a missionary settlement on the Orinoco in Venezuela, where he is treated by the pacifist Quaker Dr. Hayden.

When Murphy discovers that the U-boat is hiding farther up river under the cover of the jungle, he obsessively plots to sink it by any means, including by using a surviving Grumman J2F Duck floatplane from the Mount Kyle. The floatplane's wounded pilot was shot dead in his hospital bed by the U-boat captain, compounding the earlier war crime of shooting the survivors in the water, in order to preserve the secret of the submarine's location. Murphy tries to fly the aircraft on the choppy river water and learns how to manipulate the controls by trial and error. He soon finds the U-boat's hiding place and attempts to bomb it using homemade Molotov cocktail bombs, but his effort fails and the mission settlement is destroyed in retaliation.

Word comes that Germany has surrendered, but Murphy is obsessed with revenge and plans to ram the U-boat with a floating crane owned by Louis, a friendly Frenchman. This attempt also fails when the U-boat dives under him. However, the submerged U-boat is ensnared in a mud bank. Murphy uses the crane to recover an unexploded torpedo fired earlier by the U-boat and drops it on the trapped crew, killing them. Murphy is also killed as the explosion from the torpedo causes the crane jib to pin him to the deck as the floating crane sinks to the river bed.

Film rights to the novel were purchased by Paramount Pictures. In 1969, Frank Sinatra was recruited to star in the film, but he withdrew from the project. Eventually Robert Evans, head of Paramount, offered the project to the team of Peter Yates and Michael Deeley, who had made Robbery for the studio. Deeley says a script had already been written by Stirling Silliphant, who worked on subsequent drafts with Yates. Silliphant later recalled:

Our purpose was to make a flat-out statement about the absurdity, the meaninglessness, of war. So we went for minimal sound, minimal dialogue, a kind of intense fumbling toward death, toward the showdown between enemies who have no further reason for enmity except the blind stupidity and vengefulness of the Peter O’Toole character. And this is why, at the end, in a high angle shot director Peter Yates closed out the film with the sub sinking, the barge sinking, and the river surging above both, covering them for all eternity. Over this he shot a ragged flight of jungle birds, wheeling off, the only survivors of this pointless encounter between men and their machines.

Yates said that he was particularly interested in "the way in which three people—Murphy, a doctor and a Frenchman left in the backwash of war—are really brought together by circumstance and how each character plays on the other and makes them do things that they wish they hadn't and things they sometimes feel proud of."