Started As Frères Baume in 1830 in Geneva, by brothers Louis-Victor and Célestin Baume, the manufacturer later partnered with Paul Mercier in 1918, turning out to be the Baume & Mercier we know today. All through a very difficult period for that manufacturer, Baume & Mercier joined the Richemont group https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/