During a thunderstorm in early September 1944, units of the 35th Infantry Division are nearing the French town of Nancy. One of the division's mechanized reconnaissance platoons is ordered to hold their position when the Germans counterattack. The outnumbered platoon also receives friendly fire from their own mortars.
Private Kelly, a former lieutenant scapegoated for a failed infantry assault, captures Colonel Dankhopf of Wehrmacht Intelligence. Interrogating his prisoner, Kelly notices the officer's briefcase has several gold bars disguised under lead plating. Curious, he gets the colonel drunk and learns that there is a cache of 14,000 gold bars, worth $16,000,000, stored in a bank vault 30 miles behind enemy lines in the town of Clermont. When their position is overrun and the Americans pull back, a Tiger I kills Dankhopf.
Kelly decides to go after the gold. He visits the opportunistic Supply Sergeant "Crapgame" to obtain the supplies and guns that will be needed for the operation. A spaced-out tank platoon commander known as "Oddball" and his three M4 Sherman tanks from the 6th Armored Division invite themselves into the plan. With their commanding officer, Captain Maitland, busy pursuing opportunities to enrich himself and thus severely neglecting the welfare of his troopers, the men of Kelly's platoon are all eager to join Kelly. After much argument, Kelly finally persuades cynical Master Sergeant "Big Joe" to go along.
Kelly decides that his infantrymen and Oddball's tanks will proceed separately and meet near Clermont. Oddball's tanks fight their way through the German lines, managing to destroy a German railway depot, but their route is blocked when the bridge they need to cross is blown up by Allied fighter-bombers. This forces Oddball to bring a bridging unit in on the caper. An American fighter plane mistakes Kelly's group for the enemy, destroying their vehicles and forcing them to continue on foot. They stray into a minefield, and Private Grace is killed. Kelly's troops engage an enemy patrol; Private Mitchell and Corporal Job, still stuck in the minefield, are killed.
The two units rendezvous two nights later. They battle their way across the river to Clermont, losing two of the three tanks and leaving the bridging unit behind. When intercepted radio messages from the private raid are brought to the attention of the gung-ho Major General Colt, he misinterprets them as the efforts of aggressive patrols pushing forward on their own initiative and immediately rushes to the front to exploit the "breakthrough".
Kelly's men find that Clermont is defended by three Tiger tanks of the 1st SS Panzer Division with infantry support. The Americans are able to eliminate the German infantry and two of the Tigers, but the final tank parks itself right in front of the bank and Oddball's Sherman breaks down, leaving them stalemated. At Crapgame’s suggestion, Kelly offers the German tank commander and his crew an equal share of the loot.
After the Tiger blows the bank doors open, the Germans and Americans divide the spoils and go their separate ways, just barely managing to avoid meeting the still-oblivious General Colt, who is blocked from entering Clermont by the French residents who have been deceived by Big Joe into thinking that General Charles de Gaulle is coming. Not long after the freelancers have gone, Captain Maitland enters the bank, to find a Kilroy and the words "Up Yours, Baby" painted by one of Kelly's crew on the wall.
The project was announced by MGM in November 1968 under the title of The Warriors.
George Kennedy turned down a role despite an offered fee of $300,000 because he did not like the part.
The film was going to have a female role, but prior to filming, it was cut from the script. Ingrid Pitt, who was cast in the role (and had been in the movie Where Eagles Dare with Eastwood the previous year), revealed that she was "virtually climbing on board the plane bound for Yugoslavia when word came through that my part had been cut".
Filming commenced in July 1969 and was completed in December. It was shot on location in the Istrian village of Vižinada in Croatia (then part of Yugoslavia) and London. Yugoslavia was chosen mostly because earnings from previous showings of movies there could not be taken out of the country, but could be used to fund the production. Another reason Yugoslavia was selected was that in 1969, Yugoslavia was one of the few nations whose army was still equipped with operating World War II mechanized equipment, both German and American. This simplified logistics tremendously.
The film was made and released during a time of great turbulence for MGM.
There is a nod to the ending of The Good, the Bad and the Ugly, right down to a very similar musical score, and the overdubbing of the sound of non-existent jangling spurs.
Approximately 20 minutes were cut from the film by Metro-Goldwyn-Mayer before theatrical release. Eastwood said later in interviews that he was very disappointed about the re-cut by MGM because he felt that many of the deleted scenes not only gave depth to the characters, but also made the movie much better. Some of the deleted scenes were shown on promotional stills and described in interviews with cast and crew for Cinema Retro's special edition article about Kelly's Heroes:Oddball and his crew pack up to go across the lines to meet up with Kelly and others while local village girls are running around half naked.
The platoon encounters a group of German soldiers and naked girls swimming in a pool.
While they wait for Oddball in the barn at night, Kelly and Big Joe talk about their disillusionment with the war and why Kelly was made as a scapegoat for the attack that resulted in his demotion. Another scene was deleted from this part where the platoon decides they do not want to continue with the mission, and Gutowski threatens Kelly at gunpoint, but Big Joe and Crapgame side with Kelly.
General Colt is in bed with some women when he gets a call that Kelly and others have broken through the enemy lines.
During the attack on the town, production designer Jon Barry had a cameo as a British airman hiding from the Germans.
One promotional still shows Kelly finding a wounded German soldier among the ruined houses during the final town attack.
Kelly, Oddball and Big Joe discuss tactics while standing on an abandoned Tiger tank before the scene where they negotiate with the German tank commander.
When Kelly and platoon drive off at the end, a bunch of soldiers yell at them that they are headed in the wrong direction.
The film received mostly positive reviews. It was voted at number 34 in Channel 4's 100 Greatest War Films of All Time. The film earned $5.2 million in US theatrical rentals, making it the 25th highest-grossing film of 1970. Review aggregation website Rotten Tomatoes gave the film an approval rating of 80% based on 20 reviews, with an average rating of 6.9/10.
The film score was composed, arranged and conducted by Lalo Schifrin and the soundtrack album was released on the MGM label in 1970.
The soundtrack was released on LP, as well a subsequent CD featuring the LP tracks, by Chapter III Records. This album was mostly re-recordings. An expanded edition of the soundtrack was released by Film Score Monthly in 2005. The main musical theme of the movie (at both beginning and end) is "Burning Bridges," sung by the Mike Curb Congregation with music by Schifrin. There is also a casual rendition of the music in the background near the middle of the film. The Mike Curb Congregation's recording of "Burning Bridges" reached number 34 on the Billboard Hot 100 singles chart on March 6, 1971, but did much better on the charts in Australia, where it spent two weeks at No. 1 in May that year. In Canada, the song reached number 23 in March 1971.
The soundtrack to the film also contains the song, "All for the Love of Sunshine," which became the first No. 1 country hit for Hank Williams, Jr.. The inclusion of the song in the film is an anachronism, because the song was not released until 1970, twenty-five years after the end of the war.
All compositions by Lalo Schifrin except as indicatedIn the 2012 anime series Girls und Panzer, the film is referenced several times, including by supporting character Yukari Akiyama once calling herself "Sergeant Oddball" and as reference material for urban tank-to-tank combat by the protagonist Rabbit Team. The latter reference is made during a slumber party when the girls are watching Kelly's Heroes on DVD, depicted by an animated version of the sequence in which Kelly and Oddball take out the second Tiger tank in the streets of Clermont.
Kelly's Heroes was released to DVD by Warner Home Video on August 1, 2000, in a Region 1 widescreen DVD (one of several solo DVD's marketed as the Clint Eastwood Collection) and also to Blu-ray on June 1, 2010 as part of a double feature with Where Eagles Dare.