 On the outbreak of the Second World War in 1939 the castle was readied for war @-@ time conditions . Many of the staff from Buckingham Palace were moved to Windsor for safety , security was tightened and windows were blacked @-@ out . There was significant concern that the castle might be damaged or destroyed during the war ; the more important art works were removed from the castle for safe @-@ keeping , the valuable chandeliers were lowered to the floor in case of bomb damage and a sequence of paintings by John Piper were commissioned from 1942 – 4 to record the castle 's appearance . The king and queen and their children Princesses Elizabeth and Margaret lived for safety in the castle , with the roof above their rooms specially strengthened in case of attack . The king and queen drove daily to London , returning to Windsor to sleep , although at the time this was a well @-@ kept secret , as for propaganda and morale purposes it was reported that the king was still residing full @-@ time at Buckingham Palace . The castle was also used as a storage facility ; for example , the only purified heavy water at the time was rescued from France in the face of the imminent French defeat in 1940 , and most of it was sent to the castle to be stored in the basement alongside the Crown Jewels . After the war the king revived the " dine and sleep " events at Windsor , following comments that the castle had become " almost like a vast , empty museum " ; nonetheless , it took many years to restore Windsor Castle to its pre @-@ war condition . 
