When Germany invaded Denmark on the morning of 9 April 1940, the Luftwaffe mounted one of the first airborne operations in history and took Aalborg by parachute. This was not an incidental target. The Norwegian campaign was being fought at the same time, and Aalborg sat exactly where a transport aircraft flying troops and equipment from Germany to Norway needed to stop for fuel. Squadron after squadron of Junkers Ju 52/3m staged through the field. The Germans renamed it Fliegerhorst Aalborg West and set about enlarging it on a scale that reveals what they thought it was worth: from 140 hectares to 2,750. A market-town airstrip built to fly businessmen to Copenhagen became, within weeks, the hinge of an invasion two countries away.

The Allies understood the airfield's value too, and paid for the understanding. On 13 August 1940 a formation of Royal Air Force Bristol Blenheim bombers attacked the German aircraft based at Aalborg in daylight. Anti-aircraft fire and Messerschmitt Bf 109 fighters met them over the field. Eleven aircraft made the attack, and all eleven were shot down — every machine that crossed the Danish coast that morning came apart over the airfield or the water around it. Every crew that set out for Aalborg that day was lost with their aircraft — a daylight attack by slow, lightly armed bombers against a target the Luftwaffe had every reason to defend heavily.

Four years later the RAF came back with a faster aircraft. On 16 June 1944 de Havilland Mosquitoes struck the airfield, and among the pilots leading aircraft of No. 305 Polish Bomber Squadron was Michael Herrick, a New Zealand fighter ace. He had flown night fighters during the Battle of Britain as a very young man, then completed two operational tours on Curtiss P-40 Kittyhawks in the Pacific, then returned to Britain to fly Mosquitoes against the Luftwaffe. It is a career that reads like three separate wars stacked into one life. He was killed over Aalborg.

By the time the Royal Air Force arrived in 1945, most of the military and airport equipment had been destroyed by the retreating occupiers — but the ground itself remained, and Aalborg was by a wide margin the largest airfield in Denmark. Before it became anything else, it became a camp: Baltic German refugees, displaced by the collapse of the eastern front and unwanted almost everywhere, were interned at the site. When the Royal Danish Air Force was formed in 1950 it took over the old Fliegerhorst intact, inheriting runways that a hostile power had built for a purpose nobody in Aalborg had ever wanted.

Today the base carries the name Air Transport Wing Aalborg, and its role has shifted from interception to reach. The resident 721 Squadron is an air transport unit, flying four Lockheed C-130J-30 Hercules and four CL-604 Challengers — the long-range lift of a small air force whose responsibilities run from Jutland out across the North Atlantic. The Jaeger Corps, Denmark's army special forces unit, is also based here, which puts transport aircraft and the people who jump out of them on the same field. The fighters have gone: 723 and 726 Squadrons, flying F-16MLU Fighting Falcons in the reconnaissance and fighter roles, were decommissioned on 10 January 2006 and their aircraft moved south to Skrydstrup. The base shares its runways, air traffic control and several other services with the civil Aalborg Airport next door, so a Hercules and a holiday charter queue for the same strip of concrete — a workable arrangement, and a very Danish one.