While hoping to stay the Russian advance in the east, Hitler had one last hope of striking a decisive blow at the great arsenal from which he apprehended the final assault: Britain. German scientists had long been working on flying bombs and rockets, and Hitler had spoken of having in reserve a secret weapon which would redress the failing balance for Germany. The nature of this secret weapon was not unknown to the British who, in 1943-44, by bombing the factories where it was being developed, held up its manufacture. But by 1st December, 1943, the German program was complete and on that date Hitler approved orders to prepare and carry out long range warfare against England with all the special weapons involved therein. The Commander In Chief West was authorised to take all the necessary measures, and heavily fortified sites were constructed in northern France from which to fire the missiles. A further Order was issued on 23rd December, and definite instructions were issued by Hitler in May, 1944.