ROF Chorley was a UK government-owned munitions filling Royal Ordnance Factory (Filling Factory No. 1). It was planned as a "permanent" Royal Ordnance Factory with the intention that it, unlike some other similar facilities, would remain open for production after the end of World War II; and, together with ROF Bridgend (Filling Factory No. 2), would replace the Royal Filling Factory located at the Royal Arsenal, Woolwich. It was built adjacent to the village of Euxton but was known as ROF Chorley.