Combined Operations, which was responsible for control of the Western Approaches, was moved in 1941 from Plymouth to Derby House, part of Exchange Buildings Liverpool. The move was instigated by the fact that German aircraft and U-boats (submarines) were attacking ships travelling to Britain from the French coast, hence, ships were re-directed around the north of Ireland. Western Approaches Command HQ was therefore moved to Liverpool on 7 February 1941. The complex - which was known locally as the "Citadel" or "Fortress", due to the extensive reinforced-concrete protection given to the basement, which was to become the Operations Room. It was designed to be bomb proof and gas proof, with a 7-foot thick roof and 3-foot thick walls, and 100 rooms covering an area of 50,000 square feet. The Royal Navy, Air Force and Royal Marines worked jointly there to monitor enemy convoys and "wolf packs" of U-Boats, which threatened to bring Britain to her knees in the early part of the war. The bunker played a big part of the winning of the Battle of the Atlantic, its role being to ensure the successful delivery of supplies and equipment into wartime Britain from the sea. To win the Battle of the Atlantic was paramount for Britain to survive, it carried far more significance than winning the Battle of Britain in the air. The invasion of Europe in 1944, spelling out, the beginning of the end for Germany; could not have been mounted if the German U-Boats had been the victors of the Battle of the Atlantic. During the war, three different men held the position of Commander-in-Chief for Western Approaches Command. Admiral Sir Martin Dunbar-Smith was Commander-in-Chief in Plymouth, and remained so during the early changeover period, from 7 February to 17 February 1941. Admiral Sir Percy Noble held the position from 17 February 1941 to 19 November 1942, and finally Admiral Sir Max Horton, who was to be given the Freedom of the City of Liverpool after the war, was Commander-in-Chief from 19 November 1942 until Western Approaches Command closed on 15 August 1945. His dynamic leadership played a vital role in the final defeat of the U-Boat menace. Throughout the years of WW2, Liverpool was Britain's main convoy port, the vital lifeline was maintained with the United States and Canada, it was crucial both for Britain's survival and the ultimate Allied victory. During WW2, over 1,000 convoys arrived in the Mersey, on average 3 or 4 per week. Many warships and Merchant ships were repaired and built on Merseyside, and thousands of Liverpool people were involved. Today, the historical war time bunker has been restored and opened to the public as a memorial to those who died to achieve it. It is the original building where the original battle was fought and won. It has been reconstructed exactly as it was when operational. (Rob and I were in no danger of being dragged off to the Tower, photography is allowed..........."I think.." :-0