Cambrai Start Formations
Prior to Cambrai, on 30th October 1917, the Tank Brigades were issued with a copy of "Tank and Infantry Operations without Methodical Artillery Preparation" (OH p349ff)
This document was designed as a guide and was supposed to be modified to allow for differing tactical conditions.
The document includes several diagrams, one of which shows a company of tanks leading an infantry battalion; this is the only diagram which shows such a formation and is the only one reproduced in the Official History. The infantry battalion is deployed with two companies in advance and two in support, each company is deployed with two platoons in advance and two in support, and each platoon is deployed with two sections in advance with two sections in support, each advancing in column following the tanks. Each platoon is led by one tank, eight across the front of the whole battalion, these tanks are designated as main body tanks. 100 yds in advance of the main body tanks are deployed four advanced guard tanks, one for each pair of main body tanks, thus each section of three tanks forms a triangular wedge. The diagram doesn't indicate how far behind the tanks the leading infantry sections were to be, the document simply states the infantry were to follow immediately behind the tank (para 14), and ensure they stayed at least 25 to 30 paces behind the tank when it was crossing wire to ensure they did not get tangled in any strands (para 18).
On 20th November each on the five infantry divisions attacked the first objective (Blue Line) with two brigades alongside one another in advance and the second objective (Brown line) with the remaining brigade. Each Brigade was supported by two tank companies. i.e. one per attacking battalion, (One of 62nd Division's Brigades was only supported by a single company, 19 from "G" Battalion, but this had been reinforced to a strength of 30 tanks); survivors from the first wave of tanks were also to support the attack on the second objective.
Only "C" and "F" Battalions, operating with 12th Infantry Division, on the far right flank appear to have adopted the tactical scheme relatively unaltered. Both battalions deploying 24 tanks in front of the first wave of infantry, the distance the infantry were to follow behind the tanks is not given.
"A" and "I" Battalions, operating with 20th Division, and "H" and "B" Battalions operating with 6th Division, each deployed eighteen tanks in front of the leading infantry wave and six behind the wave in support. The supporting six tanks were to start 20 minutes after the leading wave of tanks; i.e at D+10 as opposed to D-10. The majority of the leading sections attacked in wedge; but where tactics and terrain dictated it some did advance in column (i.e. "B" battalions flank sections).
The infantry were to follow 75 yards behind the main body tanks according to "A" Battalion's war diary (W1) or 70 yds according to Capt. Hickey ( though he did advance with the second wave). (S61.p101).
"D" and "E" Battalions also deployed eighteen tanks immediately in front of each brigade. However the other six tanks were not deployed as a reserve but were instead deployed 100 to 200 yds in front of the main body tanks and were ordered to crush the wire and subdue the MGs in front of the enemy's main line; it is worth noting that this is much the same mission as given to the advanced guard tanks. A diagram attached to the 1st Tank Brigade's Report on Operations indicates there were no advanced guard tanks, each section of three tanks were deployed in line abreast, not the wedge formation used elsewhere; the infantry in the leading sections were to follow in line 150 - 200 yds behind the tanks; one platoon of infantry following each three tank section.
The actual formations adopted can be found in the links below.
Cambrai start formation. A Battalion
Cambrai start formation. B Battalion
Cambrai start formation. C Battalion
Cambrai start formation. D Battalion
Cambrai start formation. E Battalion
Cambrai start formation. F Battalion
Cambrai start formation. G Battalion. 19 Company
Cambrai start formation. G Battalion 20 and 21 Companies
Cambrai start formation. H Battalion