It may seem surprising, but Disney Animation has never won an Oscar for best animated feature -- a failing that was remedied on Monday morning when it won for critical and box office hit Frozen. 

That is partly because the Oscar category was only created in 2002 and since then Disney has failed to win -- although Pixar, which it bought in 2006, has won seven times in 11 years. 

It is a record which is all the more surprising since Walt Disney himself won no fewer than 22 Oscars over his long career, for shorts and documentaries, plus a few honorary Academy Awards. But Frozen -- loosely based on Hans Christian Andersen's The Snow Queen -- has finally succeeded in ending the Disney drought, with a film which has taken nearly $1 billion at the box office, beating Disney Animation's previous record held by The Lion King since 1994. 

The film's success marks the culmination of a revival driven by fierce competition and the studio's purchase of rival Pixar, bringing boss John Lasseter into the Disney fold.
Critics have hailed it as one of Disney's best ever movies, following the success of The
Princess and the Frog (2009), Tangled in 2010 and 2012's Wreck-It Ralph. 

Disney has come a long way since the turn of the millennium, when the studio had been
sidelined by Pixar and its string of blockbuster hits, from Toy Story and Cars to Finding Nemo, Ratatouille and Up.

It is not Disney's first comeback. The 1970s and 1980s were tough for the studio, until a new generation of animators arrived to create films like The Little Mermaid (1989), Beauty and the Beast (1991) and 1994's majestic success The Lion King. 

Ironically, the Prince Charming of this latest rebirth had been the studio's main rival: Lasseter, co-founder of Pixar, who was named Disney's animated creative director after his company became part of Mickey's empire eight years ago. 

Music is at the heart of Frozen, which tells the story of princess Anna, who sets off on a journey to find her sister Elsa, whose hard-to-control icy powers have trapped the kingdom in a wintry spell.The movie's signature tune Let It Go was nominated for the best song Oscar.

Producer Peter Del Vecho said Lasseter had "changed the culture at Disney Animation. We're a different studio than Pixar, but a lot of the same ideas that he learned there, he imported to us. "The main thing he imported was that we as filmmakers have to take ownership of our product. John sets a very high bar in terms of story, in terms of research, and you always want to hit that bar," he said. 

The other factor driving Disney's renaissance has been increasingly tough competition from rivals like Blue Sky (Ice Age, Rio), DreamWorks Animation (Shrek, Kung-Fu Panda, Madagascar) and Illumination, which makes the Despicable Me films -- the second of which was also nominated on Sunday.

"A rising tide raises all boats. It is very important for the art of animation to have competitors at other studios," said Tom Sito, professor of cinema at the University of Southern California (USC), a former Disney animator.