Wojtek, a Syrian brown bear, was adopted as a cub by the Polish army in 1943.
Taught by his Polish comrades, Wojtek learned to wrestle, salute, smoke and drink and found fame after he reportedly carried ammunition under a storm of enemy fire during the 1944 battle of Monte Cassino.
That same year, after troops warmed to his larger-than-life personality, the bear was made an honorary soldier.
He and his comrades later spent time in the Borders following the end of the war.
Mrs Orr wrote the book six years ago, having been inspired by stories told to her by her grandfather, Jim Little, who served in the British Army all his life. As his only grandchild, she grew up listening intently to them.
She said: “He met Wojtek while in the Middle East, where he spent about eight months tasked with getting soldiers fit for battle.
“As with many who have served in the Army, he didn’t like to talk about the war, so telling these stories to me about the bear was a much easier way to do so.”
Mrs Orr visited the bear at Edinburgh Zoo as a child and was surprised to later learn that Sunwick Farm, near Hutton in Berwickshire, where she lives, was home to Winfield Airfield, where Wojtek and his team were flown to after the war ended.
The 500lb bear became popular among residents of Berwickshire before being sent to Edinburgh Zoo in 1947.
The upcoming film, Soldier Bear, will be directed by Brendan Foley, best known for movies including 2006’s The Riddle and 2005’s Johnny Was, both starring former footballer Vinnie Jones.
The Northern Irish director first came across the book after his wife recommended he read it.
The author said: “I have been approached twice in the past regarding deals from the book, but I turned them down as I didn’t like what they were doing to the story.
“Foley has already worked on war films and has a really good historical understanding and genuine empathy.”
Mr Foley said: “It’s just rare to find such an amazing, compelling story.
“War Horse is a very popular film, and I think ours has advantage that bears have much more relatable animals to humans.
“They have very human traits, walk on their hind legs and have very expressive faces that can portray many emotions – and people just love bears.
“Wojtek has a very large international fan club.
“This story has the advantage of taking him from a tiny cub who looks like teddy bear to a great 500lb bruiser with claws.”
Polish film company Filmpolska will co-fund the development of the film with a budget of more than £10m.
Pre-production is currently under way, and much of the groundwork has already been done.
Regarding the film’s director, Mrs Orr added: “I’ve got great faith in him, and I know he will do a good job of it.
“It’s a story that needs to be told, and it’s a very dark story.
“People here all remember the bear from when they were little children.”
Most of the film will be set in north Africa, Italy and Scotland.
Belfast-born Foley flew from the US this week to meet Mrs Orr to discuss the next stage of the project.