Aalborg Airport, officially opened in 1938 because of the success of the cement industry, had in fact operated flights to Copenhagen since 1936. During the German invasion of Denmark in 1940, the airport was captured by German paratroopers on the night of 21 April as a base for German aircraft flying to Norway. On 13 August 1940, a dozen Bristol Blenheim bombers of No. 82 Squadron RAF were launched against the Luftwaffe airfield during one of the most disastrous Royal Air Force raids of the war. One turned back because of fuel problems, but all of the remaining 11 were shot down by enemy fighters and/or flak batteries within 20 minutes. After the war, the Royal Air Force destroyed all the German facilities including planes, hangars and equipment but left the passenger facilities intact.