In 1940, the Netherlands was invaded by Germany with Nijmegen being the first Dutch city to fall into German hands. On 22 February 1944, Nijmegen was heavily bombed by American planes, causing great damage to the city centre. It was subsequently claimed by the Allies that the American pilots thought they were bombing the German city of Kleve, while the Germans alleged that it was a planned operation authorised by the Dutch government in exile. The Dutch organization for investigating wartime atrocities, the NIOD, announced in January 2005 that its study of the incident confirmed that it was an accident caused by poor communications and chaos in the airspace. Over 750 people died in the bombardment.