The 2C bis was based on the Char 2C. In 1926, the later Champagne was modified into the Char 2C bis, an experimental type with a 155 mm howitzer in a cast turret, new engines were fitted and the machine gun positions deleted. In this configuration the tank weighed perhaps 74 tons. The change was only temporary though, as the vehicle was brought back into its previous condition the very same year; the new turret was used in the Tunisian Mareth Line.
Between 15 November and 15 December 1939 the Lorraine, as the company command tank, was experimentally up-armoured at the Société des Aciéries d'Homecourt to make it immune to standard German antitank guns. The front armour was enhanced to 90 mm, the side to 65 mm. In this configuration, weighing about 75 tons, the Lorraine had at that time the thickest armour of any operational tank, and is probably still the heaviest operational tank ever.