Tivvy,
Welcome to the Forum.
The 12th Manchesters were part of the 17th (Northern) Division which consisted of three brigades, one of which was 52 Brigade. It was in this brigade that the 12th Manchesters served.
At 4 am on the 25th August 1918 the battalion was in an attack on the Thiepval Ridge. The progress of the advance was excellent, Martinpuich being captured. At 5 am on the 26th August the advance continued. However, it started badly, but all resistance was eventually overcome and a further advance of 2500 yards was made. Unfortunately, casualties were suffered and 19 Other Ranks were killed, which must have included Pte Rainsbury. PhilipG