The United States entered the Second World War late in 1941, and during 1942 embarked on Operation Bolero, the creation of facilities for the assembly of army and air force units in Great Britain for future assaults on continental Europe. The prototype storage base was begun at Wem, 16 km north of Shrewsbury on 14 December 1942 and was completed on 30 June 1943. It extended over 22 ha, had a camp for 1,250 men, and 17 km of railway sidings.
The industrial estate that now occupies the site provides a rich archaeological record of the Second World War, although some of the land has been returned to agriculture and some is occupied by a caravan site. The railway embankments linking the depot to the line from Shrewsbury to Crewe, and to the ports on the Mersey, the Clyde and in South Wales, can still be recognised. The line was worked in wartime by three 0-6-0T tank locomotives made in Pittsburg and delivered during 1943. The estate includes six ranks of corrugated asbestos huts with corrugated iron end walls in which are doors sufficiently large to admit vehicles. Each hut has four ventilators in the roof, 24 skylights and two concrete pipes which would have been flues for coke stoves. All had telephones and swan-necked lamp standards for external lighting. The only other buildings remaining from the military period are small brick structures such as toilet blocks and emergency water-supply installations. Present day users include a timber company, transport depots, vehicle body builders, steel fabricators and a wholesale florist. The site is in private ownership but the public have access to the businesses on the estate, and a café provides refreshments.