During the First World War, after the establishment in 1915 of the Ministry of Munitions under the direction of David Lloyd George (1863-1945), the British government built some 240 ‘National Factories’ for the manufacture of munitions, of which more than 20 were for the filling shells and other artillery projectiles. Most such factories were demolished and the sites cleared after the Armistice of 1918, but three, including that at Rotherwas established on the southern edge of Hereford in 1916, were retained on a care-and-maintenance basis during the 1920s and 30s. Rotherwas was revived as a Royal Ordnance Factory (Filling Factory No 4) with the onset of the Second World War in 1939, and filled large bombs and 15 inch (38 mm) shells for naval guns.
When production ceased the 142 ha site was purchased by Herefordshire County Council (now Herefordshire Council) in 1973, and much of it on either side of the B4399 road is now the Rotherwas Industrial Estate, providing premises for more than 200 companies. It provides archaeological evidence of filling factories of both the World Wars of the 20th century. The headquarters building of the National Factory remains, an elegant structure now used as offices. A shell store measuring 115 m X 37.5 m still stands, with a lattice steel roof giving a floor space entirely unencumbered by vertical columns. From it extend tarmac pathways along which materials were pushed in wooden-wheeled trolleys to wooden filling sheds which have been removed, protected by earthen banks which remain. On the southern extremity there remain some explosives stores, wooden buildings once served by railway sidings which can still be traced, and now providing safe custody for fireworks. The picric acid stores of the First World War are not part of the estate, but still stand in areas now restored to pasture, and serve as stables. A walk around the estate roads reveals other wartime buildings adapted to new purposes. The only facility for visitors is a café in the Rural Enterprise section of the estate.