Pirates of the Caribbean: The Curse of the Black Pearl star Keira Knightley believed that the movie was going to be a flop. Based on the Walt Disney World ride, the first Pirates of the Caribbean film was released in 2003, telling the story of Captain Jack Sparrow (Johnny Depp) who attempts to retrieve his ship, the Black Pearl, from a group of enemy pirates. Knightley's Swann gets wrapped up in the tale when these very same pirates kidnap her, which then prompts Orlando Bloom's Will Turner to go after her. The first movie was a massive success at the box office and ended up spawning four sequels.

During The Laughter & Secrets of Love Actually: 20 Years Later – A Diane Sawyer Special (via ET), Love Actually writer and director Richard Curtis recalls that Knightley, who appears in his film as Juliet, said to him that she didn't think the first Pirates of the Caribbean was going to be successful. According to Curtis, Knightley thought the film would flop because it was about pirates. Check out Curtis' recollection of the conversation below:

"I remember sitting down with Keira while we were shooting and saying, 'What are you doing next?’ And she said, 'I don't think it's going to work. It's a pirate film and they always fail.'"

Related: Pirates Of The Caribbean: How Old Will & Elizabeth Are In Each Movie

Why Pirates of the Caribbean Became A Hit Franchise

Jack Sparrow, Will Turner and Other Pirates Face Each Other on the Beach in Pirates of the Caribbean: Dead Man's Chest

Despite Knightley's reservations, the first Pirates of the Caribbean movie would go on to earn over $654 million at the box office. The subsequent entries would earn even more, with Pirates of the Caribbean: Dead Man's Chest standing as the highest-grossing of the franchise at $1.06 billion. The Gore Verbinski pirate adventure film was aimed at audiences of all ages and featured heaps of humor and even more action, with interesting lore and mythology also built into the story. Pirates of the Caribbean's colorful main characters, however, were the biggest reason for the film and the franchise's success.

While the love story between Knightley and Bloom's characters serves as the emotional core of the first three movies, it's really Depp's Sparrow who is the most memorable aspect of the franchise. Depp brought a strange and unique energy to the role of Sparrow, playing the character as if he were constantly drunk. In addition to being the source for much of the franchise's humor, Depp's character is also able to hold his own in a fight, facing off against villains like Davy Jones (Bill Nighy) and Barbossa (Geoffrey Rush). Pirates of the Caribbean's villains were also very well-realized, with Barbossa serving as a formidable foe before his eventual turn into an anti-hero in later installments, and Jones still representing the highlight of the franchise when it comes to antagonists.

What the last two installments make abundantly clear is that it's the chemistry between Depp, Knightley, and Bloom introduced in Pirates of the Caribbean: The Curse of the Black Pearl that makes the whole franchise tick. The first three movies are generally regarded as the franchise's best, but the fourth and fifth fell far short of fans' expectations, due in large part to Elizabeth and Will either being absent from the story entirely or playing minor roles. While Knightley may have had her doubts about joining Disney's pirates-themed franchise, many fans are undoubtedly happy that she decided to stick with the project.

More: Pirates Of The Caribbean: Why Elizabeth Was The Writers' Favorite Character

Source: The Laugher & Secrets of Love Actually: 20 Years Later - A Diane Sawyer Special (via ET)