On 31 July 1917 the newly formed Tank Corps fielded its biggest fleet of tanks yet deployed in to action. Of the 9 Tank Bns in existence, 5 were committed to the opening assault with 2 more being kept as Army Reserve. These 5 Bns were A, B, C, F, and G and each Bn planned to use 2 of its 3 companies in the opening assault. Thus on 31 July 1917 120 tanks went in to action.
The allocation of tanks to Corps and Divisions was as follows:
1st Tank Brigade (G Bn: supporting XVIII Corps (39, 51, 11, 48 Divs)
2nd Tank Brigade (A & B Bns) supporting II Corps (24, 30, 18, 8, 25 Divs)
3rd Tank Brigade (C & F Bns) supporting XIX Corp (15,55,16,36 Divs)
Of the 120 tanks sent in this day, just over half ditched or broke down although some of these rallied later. 28 tanks were knocked out. In general terms the tanks were able to make it to the line of the 2nd objectives.
42 tankies were killed on 31 July. 15 MCs and 39 MMs were awarded for actions that day.
It started raining on the afternoon of 31 July.