In 1939, the Lorraine 37 L was gradually introduced to the supply units of the tank battalions. This coincided with a change in tactical thinking about the use of armour. In the early thirties, French doctrine had favoured the construction of ever deeper defensive belts to counter infantry
infiltration tactics to defeat enemy attacks before they could develop into full-scale manoeuvre warfare, a field at which the French were aware of being less adept than their most likely adversary, Germany. Expecting any possible enemy to defend himself likewise, the armour branch of the French Infantry became much preoccupied with the vexing problem of how to break through similar in-depth positions itself, emphasizing close cooperation with the foot soldier. Far less attention was paid to the next phase: the envelopment of the enemy forces. The situation changed in the late thirties. Having at last built a considerable number of modern and well-armoured tanks, the Infantry became confident in its ability to break the enemy line, if sufficient artillery and air support was provided within a
combined arms tactic. At the same time the political situation made it likely that large-scale offensives were needed to bring Germany to its knees. Though few officers advocated the creation of armoured divisions able to execute both the breakthrough and the strategic exploitation phase — these required trained personnel in numbers that simply would not be available — it was understood that the "manoeuvre mass" of tanks effecting the break would immediately have to envelop the defensive enemy position and defeat counterattacking enemy armour reserves, otherwise the momentum of the attack would be lost and the breach would not be kept open long enough for the motorised divisions and cavalry armoured divisions to be launched to quickly occupy and hold strategic key positions. However, this posed a serious logistical problem: trucks would not be able to closely follow the tanks on the battlefield. The prescribed procedure for resupplying was for the tanks to return to their start positions to be refitted. While this had still been practical in the previous war with its much slower tempo of operations, it was unacceptable in modern warfare. The tanks would have to be supplied in the field to continue their advance as soon as possible. Thus a tracked supply vehicle was needed that could overcome the expected poor terrain conditions, with many shell-craters and trenches, and it had to be armoured to protect against shell-fragments, given that the breakthrough sector would likely be in range of concentrated enemy artillery. The type was provided to the armoured units of both the Infantry and the Cavalry. Each independent tank battalion of the Infantry, or , had an organic strength of twelve Lorraine tractors: four in the (supply platoon) of each of its three companies. The BCCs incorporated in the armoured divisions and equipped with the
Char B1 or Char B1 bis had 27 TRC 37Ls: each of their three companies had six tractors in its supply platoon and furthermore a single tractor organic to each of its three tank platoons. This extra allotment was made to compensate for the large fuel consumption of these heavy tanks, that, apart from being simply bigger, had also a rather limited range. Each group of three tanks was in their case thus directly followed by its own fuel supply. When, during the Battle of France, independent companies were formed, these, too, had their Lorraine tractors — an increased allotment of eight if a Char B1 bis unit, otherwise the standard allotment of four. However, the older
FT 17 battalions only used fuel trucks. Likewise, the TRC 37L was not in common use in the colonies; however, when the 67e BCC, which was equipped with the
Char D1, was brought over from
Tunisia in June, it was provided with tractors. The motorised infantry divisions did not use the TRC 37L. In the Cavalry, each squadron of twenty tanks had three Lorraine tractors, for a total of 24 for each mechanised light division. The
AMR 35 or
Panhard 178 units did not use the type, just trucks as its speed was considered insufficient. It was proposed to remedy this by fitting a stronger engine, bringing the speed to 50 km/h. The TRC 37L was also not present in the cavalry light divisions. In practice, the supply vehicles would mainly move by road and meet with the tanks at predetermined rendez-vous points. Refuelling was relatively quick as the Vulcano could theoretically pump 565 litres in fifteen minutes. To completely refill a heavy tank would normally take about forty to sixty minutes. The trailer fuel reservoirs could themselves be replenished by the company fuel truck carrying 3600 litres of petrol. The company supplies could again be restocked from battalion stocks, moved by trucks loaded with fifty litre fuel drums. This method of distribution ensured a sufficient fuel supply on the tactical level, but was too cumbersome for strategic movements: if large distances had to be covered on track, the tanks would be directly refuelled from fuel trucks. When the Germans invaded on 10 May, French tank units had an organic strength of 606 Lorraine 37Ls; the numbers produced were thus insufficient to provide each unit with its official complement. About a third had to do without. That day French general headquarters decided to increase the TRC 37L strength of and by a half; these armoured divisions had been earmarked as reserves against an expected German breakthrough attempt in the Gembloux Gap and the low range of the Char B1 bis worried French command. To free enough tractors, , still in the process of being constituted, had to give up its twelve TRC L37s to . However, contrary to French expectations, the main German breakthrough would be at
Sedan and was sent to block it — and despite its larger number of fuel tractors, was still surprised by while refuelling on 15 May. During the campaign, the TRC 37L crews quickly saw the need for some armament and began to improvise machine-gun mounts on their vehicles. ==Variants==