With the latter type, in case of war, only a limited number of armoured divisions for the Infantry Arm could be raised; the Char D2 created the prospect of increasing this.

Due to Renault's financial problems, this second, partially improved version, was only realised in early 1940, bringing total production to a hundred.

The Char D1 had already departed from the pure infantry support concept and evolved from a light into a medium tank, capable of fighting enemy armour; this made it the obvious candidate to be quickly changed into a lighter alternative for the Char B1 battle tank, needed because the latter type was in danger of being forbidden by an expected armaments limitation treaty under the auspices of the League of Nations, imposing an upper weight limit of twenty metric tonnes for armoured fighting vehicles.

[1] The Direction de l'Infanterie proposed on 23 January 1930, in a letter to the ministry of defence, to build a better armoured tank, using 40 mm plate, that nevertheless would be swifter at 22 km/h by fitting a 120 hp engine.

Existing plans to produce 750 Char D2s, 150 per year for the period 1935–1939,[2] (six hundred to equip twelve battalions and 150 as a matériel reserve) were immediately reduced.

All these decisions were taken on the basis of experience gained with the riveted prototype, though it was well understood that from it no firm conclusions could be drawn on the quality of the intended welded type.

The suspension was largely identical but the top rollers, to which a tension wheel was added, were placed somewhat higher to prevent track resonance, a persistent problem with the Char D1.

To reduce the price, Renault opted to implement a novel construction technique, using large flat screws, serving both as bolts and, applied heated, as rivets, attaching the main armour plates to each other by means of thin connecting steel strips.

The new turret also had PPLR X 160 episcopes instead of Chrétien diascopes and was fitted with a S 190 G attachment point on the roof above the back hatch, to use the reserve machine gun as an AA-weapon.

Rebuilding the original production series as flamethrowers was considered, and a single prototype had already been created of this modification; on 27 September 1939 a first batch of fifteen had been ordered and on 23 April 1940 it was decided to modify all vehicles.

In September 1939 two of the five vehicles used at the central driver school (ECC) were experimentally fitted with the longer gun, leaving three tanks to be employed for training.

[7] In the winter of 1940 it became apparent that France would have for the immediate future a lack of really powerfully armed tanks; at that moment the organic strength of SOMUA S35 or Char B1 units was just about three hundred.

From 9 March the turrets of the older vehicles were sent to the Atelier de Rueil in batches of fifteen, themselves divided into three smaller groups of five, so as to be rebuilt; at the same time it was planned to give the hulls a complete factory overhaul; due to a lack of spare parts this revision was delayed and less thorough than originally intended.

[9] After sufficient crews had been trained three tank companies were raised, which on 14 July of the same year participated in the Bastille Day parade, which was always used to publicly present new types.

Some exemplars were adorned in the most complex factory camouflage scheme, using eight different hues outlined in black, among which such surprising colours as deep purple, lilac and sky blue.

De Gaulle, France's foremost armour specialist of the day, used the type to test his ideas about tank tactics, especially in the field of radio communication.

[10] De Gaulle would use the Austerlitz, Rocroi and finally the Yorktown as his personal tank during parades, having a cushion fixed on the turret hatch he had to sit on, to accentuate his already great physical height; his legs were so long he had to let them rest on the shoulders of the driver.

[14] Moving on their tracks 120 kilometres to the frontline, thirty of the forty deployed tanks broke down: the vibrations caused by driving on a metalled road ruined the suspension systems.

It soon became clear that the type was ill-suited to conditions of snow and ice:[17] the track profiles were too flat and many vehicles were involved in serious accidents, slipping into a ravine.

[8] The decision in March to upgrade the existing tanks came as a severe disappointment as it implied that the number of operational vehicles would at first decline even further as they were gradually removed from the battalion strength to be rebuilt.

The causes were never investigated; conforming to the pervading Fifth Column atmosphere of the day, the malfunctioning was not attributed to the structurally deficient quality control at Renault combined with a hasty acceptance procedure, but to sabotage.

[22] The plan to send the company to Norway was soon cancelled as the reports of the previous winter clearly showed that the Char D2 was unsuited to snow conditions.

[23] Due to the events mentioned above, 19e BCC, a few years earlier still an elite armour unit and one of the most modern of France,[10] had at the time of the German invasion of 10 May 1940 been reduced to a rather ineffective force.

However, neither of these units at first was able to operate in a coherent whole with other divisional subunits: 345e CACC between 17 and 20 May fought independently, attacking towards Montcornet[25] on the flank of the German penetration, destroying several enemy columns swerving too much to the south; 19e BCC was in no condition to fight and kept away from the frontline, not participating in the counterattacks of 17 and 19 May by 4 DCR near Laon.

The large distances covered and the lack of time to carry out maintenance led to a quick reduction of the number of operational tanks.

This was not originally motivated by a desire to acquire a weapon able to destroy enemy pillboxes, the normal function of such systems, but inspired by the experience gained during the Spanish Civil War that tanks were quite vulnerable to attacks by portable flamethrowers.

From this, it was deduced that an entire flamethrower tank, supporting an entrenched position strengthened by anti-tank obstacles, should present a most formidable defensive arm against enemy armour.

From 1938, the state Atelier de Rueil, in cooperation with the Chaubeyre factory, constructed a single prototype from one of the original series of fifty, that was finished on 5 December 1939.

However, when war threatened it was realised that, outmoded or not, ditches would pose a serious obstacle to the French infantry tanks, especially to the shorter types, and existing prescripts about fitting them had better be followed.

A second type, weighing 210 kilogrammes, and now securing via an intermediary welded plate and bolts, was ready on 5 February and approved for production; the French defeat prevented any being fitted to the tanks.