In the past travellers avoided the Risley (Birchwood) area because it of its dangerous mossland, however gradually over time much of the fertile mossland was reclaimed and turned into farm land. With the advent of the Second World War, 927 acres (3.8 km²) of agricultural land was changed into a massive Royal Ordnance Factory, ROF Risley. The location was chosen because the low lying mist and cloud helped camouflage the factory from the air; according to a local builder: "It was very lonely and misty at night, and that's why the factory was constructed there ... it was usually covered with a mist or cloud. It was hard to see it in the day time, you know". Although the location of the factory was known by the German Luftwaffe, the factory was bombed only once during the war.