Started As Frères Baume in 1830 in Geneva, by brothers Louis-Victor and Célestin Baume, the brand afterwards partnered with Paul Mercier in 1918, starting to be the Baume & Mercier we know these days. During a particularly hard time period for your model, Baume & Mercier joined the Richemont team https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/