The luxury goods giant has threatened to quit Grasse, the luxury perfume capital of the world, if a TGV line is driven through the Provencal fields where it grows flowers for the perfume.
Chanel has the 1,000 jasmine flowers and a dozen May roses it takes for every 30-millilitre bottle of No 5 grown close to its perfumery in Grasse.
With its lavender fields and hillsides full of wild flowers, the region is one of the most mythic corners of the south of France.
In a strongly-worded open letter to planners, Chanel said a viaduct to carry trains over the picturesque Siagne valley would be a disaster.
"The construction of a viaduct and the regular passage of high-speed trains over these fields of flowers would force Chanel to cease supporting its artisanal activities in the region," the label added.
It said the quality of the flowers harvested around Grasse was "unique and exceptional... and indispensible for the creation of Chanel perfumes".
Desperate need for investment
France's state-owned SNCF railway company argues that the new 6.7-billion euro ($7 billion) line would cut an hour from the trip along the French Riviera from Marseille to Nice.
It said the line is the most congested in France outside of Paris and desperately needs investment.
Despite its high tourist numbers, the Cote d'Azur is one of the worst served by the country's highspeed rail network.
The journey time from Paris to Nice now stands at around six hours.
Chanel has already fought off plans for a dump not far from the fields where the Mul family grow the flowers.
The legendary scent was created by Coco Chanel in 1921, and quickly came to define a new type of independent, modern woman.
She commissioned Ernest Beaux -- who had been the perfumier to the Russian tsar -- to concoct a new type of perfume that broke with the strict rules of what scent was proper for a woman to wear.
"I don't want any rose or lily of the valley perfume; I want a more elaborate scent," she famously said.
Chanel had been introduced to Beaux on the Riviera close to Grasse by her then lover Grand Duke Dmitri Pavlovich Romanov, the man who had murdered the notorious Russian mystic Rasputin.
The fragrance became the most famous perfume of the 20th century, worn by Marilyn Monroe among others, with a bottle being sold every 30 seconds, according to Vogue magazine.