Despite maintaining strict neutrality during the opening months of the Second World War, on 10 May 1940, Belgium was invaded by Nazi Germany. Baudouin, his elder sister Princess Josephine-Charlotte and his younger brother Prince Albert, were immediately sent to France for safety and then to Spain. The Belgian Army, assisted by the French and British, conducted a defensive campaign lasting 18 days, but Leopold, who had taken personal command, surrendered unconditionally on 28 May. Although the Belgian government escaped to form a Belgian government in exile, Leopold elected to remain in Belgium, and was placed under house arrest at the Palace of Laeken, from where he attempted to reach an understanding with the Germans, especially in respect of Belgian prisoners of war who were being held in Germany. The children returned to Laeken from Spain on 6 August.