The French used a very wide range of tanks, including many unique types. France was the second largest tank producer in the world, behind the Soviet Union (see French armoured fighting vehicle production during World War II). Their cavalry tank class filled the role of what are now called MBTs. They also fielded a heavy tank design, and several lighter types for scouting and infantry support. In addition to these types, they were also working on super-heavy breakthrough tanks (FCM F1). The French didn't have an independent Tank Corps. All tanks belonged to either the Infantry or the Cavalry.