Char 3C / FCM 3C / "Heavy Tank D"
The German planners expected the French to resume development of improved heavy tanks. German sources described a tank labelled FCM 3C, which matched the description of the FCM 2C bis, a converted FCM 2C with a 155 mm howitzer. General Estienne had decided to revive the concept of FCM 2C, but in the form of a containment tank (Char d'arrêt). Work in this area began in 1928. In early 1932, they were implemented as a project Char BB. The 60-ton tank developed by FCM should have had a pair of 75-mm long-barreled guns, armor 60 mm thick and a crew of 8 people.
An entirely notional tank was the "Heavy Tank D". This appeared in reference books after the 1932 French proposal at Geneva for an international agreement for the destruction of all tanks heavier than 92 tons. Logically, such an agreement would only be needed if such tanks existed to be banned. Germany had been told at Versailles not build battleships above a certain power and size, and since then her engineers and scientists produced a "pocket" battleship.
The World Disarmament Conference in Geneva in February 1932 was attended by the delegates of 55 countries [nearly all independent states at the time] was convened to consider reductions in armaments, with particular emphasis on offensive weapons. The Geneva Conference attempted to classify weapons into offensive and defensive types and focused on the disarmament of offensive weapons. The object was to finally outlaw or veto the use of predominantly offensive weapons. To put it in a rather different form, a form which appealled to many people, it is to weaken attack at the expense of defence or to increase the power of defence by weakening attack. To put the same thing in yet another form it is to make it more difficult for the invader to succeed and to limit the prospects of success of a knockout blow. Deadlocked, the conference adjourned in the summer of 1932, and reconvened in February 1933, days after Adolf Hitler assumed power in Germany. The attempt to prevent war by a reduction of offensive capabilities failed, leading to the rise to power politics.
Winston Churchill told the Commons on 29 June 1931 "We all respect the motives and the movements which have promoted these conferences, and we all admire the sentiments which have been expressed at them, but up to the present they have not done any good at all. On the contrary, they have been a positive cause of friction and ill-will, and have given an undue advertisement to naval and military affairs. They have concentrated the attention of Governments in all countries, many of them without the slightest reason for apprehension about or dispute with each other, upon all sorts of hypothetical wars which certainly will never take place. The reason why these Disarmament Conferences are so fertile in provoking and promoting misunderstandings is because everyone pushes his own national point of view; everyone adopts a rather hypocritical formula of words to cover the national point of view while taking advantage of any criticisms to which the others are open....
"I have often wondered since the Great War whether it could not have been prevented by more frank and open exposures of the real dangers which were largely apparent to many of those who knew what was passing. We were restrained in those days by the fact that merely to talk about such matters' created alarm and excitement. This is undoubtedly a disadvantage, but it must be faced. Before the War, silence was preserved under thick layers of civility and discretion, padded quilts of agreeably embroidered diplomacy, and these were used to muffle all sinister or discordant sounds until in quick succession there came crisis, clamour, mobilisation, censorship, cannonade, and our lives were wrecked. Surely it ought to be our unceasing thought and effort not by any means to allow such a surprise to fall upon the populations of great countries again."
Such a tank was not under consideration at that time, but its approximate characteristics had been included in "Heigl's Taschenbuch der Tanks" Volumes 1 & 2 published 1935 and page numbering continues from V1 to V2 (720pp + ads). Volume 3 was published 1938. The book was very popular at the time, and was considered a reputable source. Unfortunately, the authors filled it with a number of their own fabrications. The 2C has the entry hatch to the rear and 3 "grenade-ports" at each side while the 3C has entry hetch at the front inside the track suspension and four "grenade-ports" to throw hand-grenades alongside the tracks to keep enemy infantry off the sides to avoid mounting the tank.
But in fact the 2Cs have three grenade-ports and a rear hatch on their starboard side, and four grenade-ports and a front hatch on their port side. They aren't even different configuration on different machines. The Char 2C was very similer to the FCMfcm 1A, had massive size, up to 45mm armor, but had two 250hp engines giving it a top speed of 15km/h. It weighed 76 tons.
The book "The Fighting Tanks 1916-1933" was published in 1933 and its authors were Major Ralph E Jones (Infantry, US Army), Captain George H Rarey (Infantry, US Army), and First Lieutenant Robert J.Icks (Infantry Reserve, US Army). It is edited by Phillip Andrews, and published by Duell, Sloan, and Pearce of New York. Besides containing lots of interesting data (including the approximate numbers of tanks in the World's armies) and photographs, it had a diagram that showed the comparative size of several different interwar tanks, including the Char 3C. Icks is usually (but not always) right on the money. However the naming (or rather numbering)of the French FMC Char de Rupture tanks is a thing of wonderous mystery as different sources give a range of numbers from Char 1C (a different tank from the Char 1A) through to the Char 3C. In the France section, the Char 3C is listed 81 tons. "Similar to 2C but 105 mm gun front turret, 75 mm rear. Some tanks had tail pieces. 1929."
General Kurt Lise, the head of the German Directorate of the Land Forces, also believed in the French "Heavy Tank D", a mythical vehicle with a crew of 15 men and four cannons. On 30 October 1935, he proposed developing a medium tank mounting a 75 mm gun with a muzzle velocity of at least 650 m/s that could effectively combat such French tanks. There was definitely a tank armed with a short 155 mm gun which is sometimes defined as a Char 2 Bis and sometimes as a Char 3C. This was in fact a Char 2C modified with a completely new turret and a new commanders position behind the turret. It possibly ceased to be a Char 2C after the mods and there was some confusuin as to what to call it. There was only one built, in 1923.
"Achtung - Panzer!" by Major-General Heinz Guderian reports the apparent major difference between the 2C and the 3C is that the 2C had a machine gun in the rear turret. Guderian lists the 3C as having a 75 mm and a 155mm cannon. Very impressive armament for an interwar tank created in 1928! Not to mention it's the dimensionally largest functional superheavy ever built, at a hefty 74 tons and 12m long, according to Guderian.