When
Germany invaded Denmark (9 April 1940), Munck had requested and was assigned by
Berlingske Tidende to Stockholm, where he met
Charles Howard Smith, the
British ambassador to Denmark (who was expelled from Denmark by the Nazi Germans on 9 April 1940). Munck developed an intelligence network, passing on information to the British, including the
Special Operations Executive (SOE) organization (22 July 1940 – 15 January 1946) after he met Sir
Charles Hambro in October 1940. Munck also planned to develop connections with other Western powers. Munck became a more effective operative, working with Danish intelligence officers, after the SOE placed a contact person, Ronald Turnbull, in Stockholm in February 1941. Microfilm and other information was passed covertly through Munck to the British via couriers. He was the conduit for all of SOE's efforts for Denmark, coordinating with all of the major Danish resistance groups and raising funds to compensate SOE for their assistance. Munck helped
John Christmas Møller escape in 1942, after which Swedish people became more involved in supporting aid for Danes. As Munck became more effective, he became known as a resistance operative. In 1942,
Berlingske Tidende was forced by its German side of the newspaper to fire Munck, who remained in Stockholm as a freelance journalist. After 29 August 1943 (when the
Germans officially dissolved the Danish government and instituted martial law), Danish intelligence officers fled to Sweden, and Munck became a representative and strategist of
Danish Freedom Council working with
Erling Foss. He increased resistance activities and developed
rescue opportunities for Danish Jews. He helped attain weapons and establish the
Den Danish Brigade (
Danish Brigade in Sweden). Munck was also involved in setting up ways for Danish refugees to cross the
Øresund and escape to Sweden. He also worked to have Denmark seen as an Allied force. From 1943, Munck became an "indispensable" leader for the Danish cause. He went to London in August 1944 to strategize with British leaders and Free Danes about how to ensure that the Danes resistance groups had the weapons and support that they needed, plan for a post-war government, propaganda, and other important issues. Involved in the discussion were Eduard Reventlow (1883-1963),
Christmas Møller, and other Free Danes. He had an in-person meeting with the Freedom Council, which meant he entered Denmark illegally, to report on the outcome of the meeting. Although he had no official position, he made a significant impact on the Danish resistance and rescue movement throughout the war. ==After the war==