The Longines story began in 1832 when Auguste Agassiz moved to the tiny Swiss town of Saint-Imier and found work at the Comptoir horloger Raiguel Jeune, a watch parts trader. A year later, he and two associates, Florian Morel and Henri Raiguel, set up the Comptoir Raiguel Jeune & Cie. One of Agassiz's sisters, Olympe, then married Charles-Marc Francillon, a Lausanne-born businessman, and in 1834 they had a son, Ernest.

When Henri Raiguel retired, in 1838, ownership of what had become Comptoir Agassiz & Cie passed to Auguste Agassiz and Florian Morel. In 1847, Auguste Agassiz became the venture’s sole owner. In 1852, his nephew Ernest Francillon joined the company, finally taking over from his uncle in 1862. Now styled Ancienne Maison Auguste Agassiz, Ernest Francillon, Successeur, the company was ready for business. At that time, watchmaking in the area was still largely a cottage industry, with all the work done at home on parts later assembled elsewhere.