On 4 September 1939, the day after the Anglo-French declarations of war, the key departments of the French Admiralty moved out of the Rue Royale to a purpose-built war location in the grounds of the duc de Noailles’s Château de Maintenon, near Chartres. The nearby small town was well served by road and rail communications with Paris, which lay 40 miles to the north-east and was expected to be made untenable by air bombardment; the French Army headquarters moved no further than to Vincennes, on the eastern outskirts of the capital, while the Armée de l’Air was 35 miles east of Paris, at St Jean les Deux Jumeaux, near Meaux. For reasons of security, the new naval headquarters was referred to only by its code-name – ‘Marceau’ – even in highly classified documents, but by the end of September, Radio Stuttgart revealed in propaganda broadcasts that the Germans were aware of the move.1 Wireless and landline communications with naval commands in France and overseas, including the direct links with Whitehall, were fully operational from the outset and there was virtually no disruption of the headquarters’ routine during the move.2