The U2s performed sterling service during the busiest years of World War II. A typical job was to take over a military train at Antrim that had been worked through from the GNR(I). Having hauled eight bogie coaches from Antrim to the summit of the NCC main line, a stop would be made at Ballyclare Junction to attach carriages that had arrived from Derry or Cookstown on a previous train before travelling on to Larne Harbour where it was common to see trains of twelve or more bogie coaches arriving.