Before the relatively quick collapse of France from the German invasion of 1940, the French Army managed a stock of one of the largest tank forces anywhere in the world. On the eve of war in September of 1939, primary French tank strength centered on the World War 1-era Renault FT-17 Light Tank, which appeared in 1,580 examples, followed by the more modern Renault R35 Light Tank which added another 1,070 to the inventory. Joining other leading tank powers of the period, the French Army also invested in several medium- and heavy-class tanks - the Char B1 being one of the latter that should have impacted the French defense more greatly than it did.
Design work on the Char B1 began as early as 1921 and spanned into 1934. Its roots in the post-World War 1 (1914-1918) years meant that the B1's appearance was greatly influenced by the heavyweight tank systems appearing in the previous global conflict. French authorities requested a gun-carrying vehicle with primary armament to be no less than a 75mm howitzer able to contend with enemy positions at range and performance capabilities to manage uneven terrain and cross trenches. A prolonged design and development period followed though nothing tangible was realized until 1930. Serial production did not happen until 1935 and would end during 1940 after which two main models emerged - the original "Char B1" and the improved "Char B1 bis". Between the two marks, 34 became the B1 model and 369 were to the B1 bis standard. Overall weight was 31 tons (short) and dimensions included a length of 21 feet, a width of 8 feet, and a height of 9 feet. The standard operating crew numbered four and armor protection reached 40mm thick (Char B1). The Char B1 bis increased armor to as much as 60mm and also included a better 300 horsepower engine (born of an aircraft powerplant) with increased fuel stores for improved range and updated secondary weaponry (47mm SA 35) in a revised turret structure. The little-remembered "Char B1 ter" mark, with its 70mm armor scheme and 350 horsepower engine, resulted in just two prototypes by the time of the French surrender.
Power for the original production tank was through an in-house Renault 6-cylinder inline gasoline engine outputting at 272 horsepower. The engine was mated to a transmission system featuring five forward speeds and single reverse speed. The hull was suspended atop a mixed coil / leaf spring system utilizing multiple bogie elements and the track links ran about the hull sides, exposed over most of its length (this quality featured on many World War 1 tanks). All told, the Char B1 could manage a maximum road speed of up to 17 miles per hour and an operational road range out to 120 miles.
The Char B1 represented one of the more powerful tanks of its time, armed principally through a 75mm ABS SA 35 howitzer which gave it considerable punch at range. However, this primary weapon was seated within the hull (at front-right side, the driver front-left side) with limited inherent traversal and elevation spans requiring the entire tank to be turned into the direction of fire. This was helped some by a quick-reacting, double differential steering system. As was the norm with other heavy tank designs of the time, secondary armament was as great as any found as primary armament on light tanks - the Char B1 carrying a 47mm SA 34 gun in a one-man, 360-degree traversing turret atop its hull. This weapon was updated in the Char B1 bis with the 47mm SA 35 series gun as mentioned previously. Local defense was handled by 1 x 7.5mm Reibel machine gun fitted coaxially in the turret.
The Char B1 was in service with the prewar and wartime French Army from 1936 to 1940 and later fell into service with the Free French Forces from 1944 to the end of the war in 1945. By the time of the German invasion of May 1940, the Char B1 was the best tank on the modern battlefield for both sides and this title was also endorsed by German General Heinz Guderian himself - the brains behind the "Blitzkrieg". The Char B1, with its stout armor protection scheme, self-sealing fuel tanks, crew protection measures, and impressive firepower made for a scenario-changing foe - German anti-tank gun crews (utilizing 20mm, 37mm, and 47mm weapons) were horrified to see their armor-piercing shells simply bouncing off the armor of the Char B1 and even the famous Panzer III and Panzer IV series of medium tanks had trouble contending with the French design - a May 16th, 1940 engagement saw a sole Char B1, waiting in ambush, successfully take out a collection of thirteen PzKpfW III and PzKpfW IV tanks.
If the vehicle held any failings, it was in its technologically-advanced design nature which restricted mass production efforts by factories, limited procurement by the Army, and complicated in-the-field operation and repairs. Break downs proved commonplace and abandoned examples were simply taken over by advancing enemy forces as their own. Its heavyweight design made for a ponderous battlefield creature and crew placement within the vehicle made communications quite difficult under chaotic battlefield conditions. The internal make up also required the commander to serve as his own gunner (sighting, loading, and firing) which added a stressful, time-consuming role to a manager already attempting to assess the battlefield situation all the while commanding his subordinates. French doctrine also stated that tanks be used in small, local-defense parties as opposed to large, coordinated formations (as in the Blitzkrieg) against enemy forces and positions. In many ways the Char B1 - as sound an instrument of war as it was - fell because of French tactics as much as it did to enemy fire and mechanical issues.
Only three heavy armored divisions were available to the French by March of 1940 and 163 Char B1 tanks were produced before the German invasion of Poland on September 1st, 1939 to officially begin World War 2. Forty-two more of these tanks followed in 1939 with another 200 in 1940. A total of 405 of these tanks would be built in all including a pair of Char B1 ter vehicles.
Beyond the logistical issues in fielding the Char B1 effectively, French tank tactics - no much evolved from the fighting of World War 1 - doomed the type to failure against the well-coordinated offensive actions of the Germans which involved combined firepower and support from aerial dive bombers, long-range artillery, mobile anti-tank teams, armored formations, and infantry elements. Following the French capitulation, the vehicle was forced into service by the Germans who used it in over a dozen tank groups of their own under the designation of "PzKpfW B1-bis 740(f)" - the lowercase "f" indicating the tank's French origins. Common practice for the Germans was to reconstitute captured weapons and rework them into other useful battlefield roles - the Char B1 therefore became the basis for a line of 105mm-armed howitzer carriers and some served as important tank driver trainers. The PzKpfW Flamm(f) became a dedicated flame tank mounting flamethrower armament which proved highly suitable for weeding out helpless, dug in infantry in fast burning structures or concealed in brush. The Italians were known to have captured up to eight Char B1 tanks at some point but at least six lacked their turrets which rendered them rather useless as combat systems. It is believed that none of these Italian offerings were used in anger during the war.
French work on heavy tanks continued shortly after the war ended in 1945, resulting in the 90mm-armed ARL 44 of which sixty were only ever produced.