As much as we see celebrities there's still so much we never know about their personal lives. That was even more true back in the golden age of cinema, but behind the glamour of the silver screen 2 Hollywood legends had a deeply vicious feud that shook the industry.

Joan Crawford and Bette Davis are two movie stars are both legends that will forever be remembered by history. Each was supremely talented and enjoyed stardom in the '30s and '40s, they even starred together in the classic What Ever Happened To Baby Jane?

You might have known all that, but what you didn't know was how much they hated each other.

Their feud led to one leaving a studio needing stitches and even affected the 1963 Academy Awards.

Why did two women who should have so much in common hate each other so much? Well it's complicated, but also quite simple.

Joan Crawford was a beautiful woman who had several torrid affairs with the leading men of the time. Bette Davis, equally beautiful often tried catching the eye of the man on Crawford's arm, but to no avail.

During the filming of Dangerous Bette Davis fell in love with her co-star Franchot Tone, he however was dating Crawford. When Crawford and Tone married in 1935 the seed for the long-running feud was planted.

In the 1940s Crawford's star was starting to fade, but Davis was in her prime. Crawford was signed by Warner Bros. studio which had been Davis's home for years. Attempting to win over the actress she knew disliked her, Crawford sent flowers and gifts to Davis's dressing room. These gestures were refused with a terse note about "lesbian overtures."

It didn't go over well.

Soon the two were frequently seen complaining about each other, in the presence of executives and even each other. Nothing was off-limits. They commented on each other's appearance, love lives, acting ability and even each other's children.

By the '60s both were nearly done in Hollywood and craved a hit. Crawford went to Davis and pitched What Ever Happened To Baby Jane? Davis was interested but she called the director, Robert Aldrich with two questions:

Would she be playing Jane, and was he sleeping with Crawford? The answers were yes and no respectively, so she signed on.

It should have been obvious that putting two hellcats in a movie together was going to end badly, but filming started anyway. After a few uneventful weeks the sparks started to fly. Constant criticism and snide remarks were so frequent that the director had to spend every night talking to each actress to convince them to stay on.

During one scene where Jane, Davis's character, beats Blanche, played by Crawford, Crawford insisted on a body double because she was convinced Davis was going to actually attack her. For one sequence the camera was too close and Crawford needed to step in. Davis clocked her so hard she needed stitches.

"What I barely touched her," Davis was heard to have said as Crawford got medical attention.

Crawford got her revenge later in the shoot. Knowing that Davis suffered from a bad back she wore a lead weighted belt during a scene where Jane had to drag Blanche's body across a room. In incredible pain Davis had nearly completed the scene when Crawford abruptly coughed - ruining the take. They had to start over.

Witnesses say Davis collapsed in agony after the shot and was furious with Crawford.

The film was a huge success, but only Davis was nominated for an Academy Award. Going into Oscar night she was the favorite, and was so sure of herself that when they started announcing the winner she handed off her purse and rose to accept the award.

She didn't win.

Joan Crawford elbowed past a stunned Davis saying "excuse me I have an award to collect."

After the show it became clear that not only did Crawford campaign against Davis winning, she had agreements with the other nominees to let Crawford accept the award. She made certain than she would be on the stage and not Davis, just to rub salt into the wound of losing.

Davis never forgave that night. The two were supposed to star together in Hush...Hush Sweet Charlotte but Davis chased Crawford away from shooting. She feigned an illness and pulled out.

They never worked together again.

The story of their feud is now a miniseries coming to TV starring Jessica Lange and Susan Sarrandon, but I'm not sure anything can be as crazy as the real story.