tractor on a training exercise in the UK. By the beginning of 1942 the imminent threat of invasion had passed, the coast artillery batteries were fully established, and the RA required gunners for the field forces. The remaining Defence Regiments in the UK were disbanded or converted into field artillery. On 12 January 1942 2nd Defence Rgt was converted into
171st Field Regiment, and 905, 907 and 908 Defence Btys were designated A, B and C; they were redesignated P, Q and R on 11 March. At this period the establishment of a field regiment was three batteries, each of two troops of four
25-pounder guns. of 45th Infantry Division. On 11 February 1942 the regiment was assigned to
45th Infantry Division, which had recently been placed on a lower establishment as a home defence formation with no immediate prospect of overseas service. At the time the division was in
II Corps District covering the Essex coast. On 1 January 1943 the regiment's batteries were numbered as 150, 151 and 152 Field Btys, and immediately 152 Bty was exchanged with 571 Bty from 195th Field Rgt, a new unit in a newly formed
80th Infantry (Reserve) Division; however the batteries exchanged numbers, so that 171st Field Rgt continued to command 150, 151 and 152 Field Btys. On 3 February 1943 the division was shipped to
Northern Ireland, where it continued training. It remained there until the end of the year, when it returned to the mainland on 21 December. The primary role of the lower-establishment divisions was now to provide trained reinforcements to units serving in active theatres. After
D Day on 6 June 1944 this was mainly to
21st Army Group fighting in
Normandy. Having supplied most of its manpower in this way, 45th Division was broken up on 30 August 1944. ==171st Heavy Regiment==