The film was very loosely based on the Swedish novel The Long Ships by Frans G. Bengtsson (1941-1945), retaining little more than the title (of the English translation) and the Moorish settings of Orm's first voyage. Although the protagonist is named Rolfe, the film was released in Sweden with the title Röde Orm och de långa skeppen (Red Orm and the Long Ships), in a further attempt to exploit the popularity of the novel. It was also intended to capitalise on the success of recent Viking and Moorish dramas such as The Vikings (1958) and El Cid (1961) and was later followed by Alfred the Great (1969).
The story centres on an immense golden bell named the Mother of Voices, which may or may not exist. Moorish king Aly Mansuh (Sidney Poitier) is convinced that it does. Having collected all the legendary material about it that he can, he plans to mount an expedition to search for it. When the shipwrecked Norseman, Rolfe (Richard Widmark), repeats the story of the bell in the marketplace, and hints that he knows its location, he is seized by Mansuh's men and brought in for questioning. Rolfe insists that he does not know and that the bell is only a myth. He manages to escape before the questioning continues under torture.
Managing to return home, Rolfe reveals to his father that he did indeed hear the bell pealing on the night his ship was wrecked in Africa. However, Rolfe's father has been made destitute after spending a fortune building a funeral ship for the Danish king, Harald Bluetooth, who then refuses to reimburse him by citing an outstanding debt. Rationalising that the ship does not yet belong to Harald (since he is still living), Rolfe and his brother steal not only the ship, but kidnap a number of inebriated Vikings to serve as its crew. In order to prevent Harald from killing his father in revenge for the theft, he also takes the king's daughter as a hostage. Harald declares that he will summon every longship he can find and rescue her. After prolonged difficulties at sea, the ship is damaged in a maelstrom. The Norse are cast ashore in Mansuh's country. Captured by the Moors, the Norse are condemned to execution but Mansuh's favourite wife Aminah (Rosanna Schiaffino) convinces her husband to use them and their longship to retrieve the bell.
Arriving at the Pillars of Hercules, Rolfe and Mansuh find only a domed chapel with a small bronze bell where the Viking was certain he had heard the Mother of Voices. Frustrated, Rolfe throws the hanging bell against a wall and the resounding cacophony reveals that the chapel dome is the disguised Mother of Voices. After a costly misadventure moving the Mother of Voices from its clifftop down to the sea, the expedition finally returns to the Moorish city, Aly Mansuh triumphantly riding through the streets with the bell in tow. As the group reaches Mansuh's palace, Aminah suddenly cries aloud that "the long ships came in the night" and is immediately shot down by a spear. A group of Vikings come leaping out from behind the silent townspeople. These Norsemen are King Harald's men, out to rescue the princess, and the climactic battle ensues. It ends when the bell falls over and crushes Aly Mansuh. The Moors are defeated and the Vikings victorious. The film ends as Rolfe tells King Harald about the "three crowns of the Saxon kings."Richard Widmark ... Rolfe
Sidney Poitier ... Aly Mansuh
Russ Tamblyn ... Orm
Rosanna Schiaffino ... Aminah
Oskar Homolka ... Krok
Edward Judd ... Sven
Lionel Jeffries ... Aziz
Beba Loncar ... Gerda
Clifford Evans ... King Harald
Gordon Jackson ... Vahlin
Colin Blakely ... Rhykka
David Lodge ... Olla
Henry Oscar ... Auctioneer
Paul Stassino ... Raschid
Jeanne Moody ... Ylva
Leonard Rossiter ... Rider of the Mare of Steel
Bruce Geller wrote the first draft of the script. Irving Allen announced he would make it for a budget of £2 million (US$5.6 million).
The film was originally meant to be directed by Jose Ferrer, who had made The Cockleshell Heroes for Irwin Allen. Ferrer said he was looking for "a Burt Lancaster type and a Tony Curtis type and two girls" for the lead. He was not intending to act in the film. However, Ferrer dropped out and was replaced by Jack Cardiff; Richard Widmark was signed to star.
The film was to be shot in Yugoslavia. George Peppard claimed he turned down a lead role despite a fee of $200,000 because he did not want to spend six months in that country.
"It is obvious that Tito's government is anxious to see more and more foreign filmmakers come to Yugoslavia," said Allen. "And of course it is also in the best interests of the American and British governments to encourage anything that improves Yugoslavia's financial independence from the Soviet bloc. I'm sure Belgrade will soon catch up with London and Rome."
Filming took place on Avala Hill.
The American Legion condemned the production of the film - along with another Hollywood financed film shot in Yugoslavia, Lancelot and Guinevere - as "immoral, deceptive, unethical and detrimental to the best interests of the United States and the free world."
"It wasn't a happy time," said Widmark of the shoot.Nominee Best Costume Design - BAFTA (Anthony Mendleson)