The political and military situation in Lausanne was very far from stable between his arrival in 1792 and the Concordat of 1801. There were times when Bigex was obliged to leave the city. At one point, when the French invaded Switzerland under General Buonaparte during the first part of 1798, Bigex lived for a time high up on the Great St Bernard, from where he returned to Lausanne and then had to move on again, this time to Geneva. Throughout this period he was nevertheless able to sustain effective communications links sufficient to enable him to provide the necessary spiritual support to the congregations in the diocese.