Started As Frères Baume in 1830 in Geneva, by brothers Louis-Victor and Célestin Baume, the model later on partnered with Paul Mercier in 1918, getting to be the Baume & Mercier we know these days. In the course of a very tough period for that model, Baume & Mercier joined https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/