With the outbreak of the Second World War in 1939, the museum began to collect material documenting the conflict. In November 1939, during the so-called "Phoney War", the museum appeared in the opening sequence of the GPO Film Unit production "The First Days", in which children are seen playing on some of the museum's German artillery pieces captured during the First World War. With the evacuation of British forces from Dunkirk in May/June 1940, however, the British Army's shortage of equipment saw eighteen of the museum's artillery pieces return to military service. The museum's trench clubs were used by the Home Guard, while other items such as sights and optical instruments were returned to the Ministry of Supply. The museum refused, however, to return some historic items such as a naval gun from HMS "Lance" (which had fired Britain's first shot of the First World War) or a gun served by Victoria Cross-winning boy seaman Jack Cornwell. The museum initially remained open but was closed for the duration of the war in September 1940 with the onset of the Blitz. On 31 January 1941 the museum was struck by a Luftwaffe bomb which fell on the naval gallery. A number of ship models were damaged by the blast and a Short Seaplane, which had flown at the Battle of Jutland, was destroyed. While closed to the public the museum's building was used for a variety of purposes connected to the war effort, such as a repair garage for government motor vehicles, a centre for Air Raid Precautions civil defence lectures and a fire fighting training school.