Construction and Early Days: 1939 - 1940
The Battle of Britain Bunker was constructed between February and August 1939 and became operational on the 25th August, just nine days before the outbreak of the Second World War.
On 1st September 1939 Nazi Germany invaded Poland. In response, the British military sent the Advanced Air Striking Force (10 squadrons of Fairy Battles) and the British Expeditionary Force, including an air component (Hurricanes, Lysanders, Gladiators and Blenheims), to France. Initially this air component was not under the control of No.11 Group at the Battle of Britain Bunker, however as the situation in Europe deteriorated No.11 Group was required to reinforce the BEF.
War was officially declared on 3rd September 1939.
The Battle of Britain Bunker was involved in the war within the first week. On 6th September 1939 the Chain Home radar system reported incoming enemy aircraft for the first time and the No.11 Group Controller, working in the Bunker, despatched 56 Squadron and 74 Squadron to deal with the threat. Unfortunately the Spitfires of 74 Squadron mistook the Hurricanes of 56 Squadron for the enemy and shot two of them down. Thus, Fighter Command’s first losses of the war were a result of friendly fire.
In April 1940 Air Vice-Marshal Keith Park was posted to No.11 Group as its Air Officer Commanding. Park would go on to distinguish himself in the Battle of Britain, devising the tactics and strategies for his controllers in the Bunker that would defeat Luftwaffe and lead to the Germans naming him “Defender of London”.
Eventually, with the BEF on the verge of disaster, the decision was taken to evacuate them from the French channel port of Dunkirk. Between 26th May – 4th June 1940 the controllers in the Battle of Britain Bunker despatched fighter squadrons as part of Operation Dynamo, with the objective of defending the evacuees against air assault.
The Battle of Britain: 10th July – 31st October 1940
In advance of Operations Sealion (the Nazi invasion of the United Kingdom), the Luftwaffe waged a 16 week campaign against the Royal Air Force aimed at destroying Fighter Command. Of the four Fighter Command groups, No.11 Group (controlled from the Battle of Britain Bunker) saw the most action due its location in the South-East of England. Throughout the conflict Fighter Command destroyed 1733 enemy aircraft, of which No.11 Group was responsible for more than two-thirds.
Between 10th July – 11th August 1940 the Luftwaffe mainly concentrated on bombing ships in the English Channel and the ports of southern England. Then, on 12th August, they switched targets and attacked the Chain Home radar system. Serious damage to the RAF’s radar system (known as Radio Direction Finding in 1940) would have seriously limited the capabilities of their operations rooms (including No.11 Group’s in the Battle of Britain Bunker) to track and intercept enemy aircraft. Fortunately No.11 Group managed to fight the enemy off with only minor damage to the radar system.
On 13th August 1940 the Luftwaffe changed targets again, this time focussing on Fighter Command’s airfields. This caused serious concern within Fighter Command – controllers at the Group operations rooms (including in the Battle of Britain Bunker) would now be making decisions that not only affected their pilots in the air, but also their airfields on the ground.
The Luftwaffe’s targeting of Fighter Command airfields was more sustained than their previous assaults, continuing daily until September. This period saw some of No.11 Group’s busiest and most successful days. The presence of AOC No.11 Group, AVM Keith Park, was in the Battle of Britain Bunker on several occasions during August and he hosted visits from the Prime Minister Winston Churchill and the King and Queen. At the end of his visit to the Battle of Britain Bunker on 16th August 1940, Churchill spoke the now famous words “Never in the field of human conflict was so much owed, by so many, to so few”. He said the phrase as he got into his car, close to the entrance of the Bunker, then repeated them in the House of Commons on 20th August.
The final phase of the Battle of Britain began on 1st September 1940, with the Luftwaffe changing targets for the final time and attacking London. Although the pressure was now off No.11 Group’s airfields, the month of September saw some of the fiercest fighting of the Battle, with Fighter Command struggling to defend the capital. As in August, AVM Keith Park’s presence was required in the Battle of Bunker on several occasions, including the 15th September when the Prime Minister visited again. Churchill would later write about the 15th September 1940 in his memoirs, relating his conversation with Park about the progress of the day’s defensive operations, but also providing clues to the ferocity, complexity and desperation of the day’s fighting. At one point he writes about the moment at which “all of the bulbs glowed red”, referring to the squadron state boards in the Operations Room and indicating that every No.11 Group squadron was engaged in combat at the same time.
Incidentally, 15th September 1940 was to be the decisive day of the Battle, with Fighter Command shooting down 56 enemy aircraft for the loss of 26 of their own. Two days later Hitler postponed Operation Sealion indefinitely. However, Luftwaffe aircraft continued to attack the UK until the end of October, particularly at night, and thus the Battle of Britain Bunker remained busy throughout this period.
The Rest of the War: 1941 – 1945
In December 1940 AVM Keith Park was replaced as AOC No.11 Group by his rival at No.12 Group during the Battle of Britain, AVM Sir Trafford Leigh-Mallory, who oversaw a thorough overhaul of the Operations Room within the Battle of Britain Bunker. The old plotting system of wooden markers and wooden croupier-style pushing sticks were replaced with metal plotting markers and magnetic sticks, and the old tote system of light-indicators was replaced with a slat-board system with hanging information. Around the same time the Battle of Britain Bunker had a royal box installed with views of the Operations Room. This was in advance of the formal visit of King George VI and Queen Elizabeth, even though both had been on informal visits in 1940.
In early 1941 No.11 Group was largely occupied with defending London against the Blitz, which had begun in September 1940 and coincided with the final stages of the Battle of Britain. However, once the Blitz had abated No.11 Group gradually began to focus on air operations over occupied Europe (although defensive operations over British airspace continued also). In August 1941 No.11 Group conducted its first fighter sweeps over enemy territory and these would continue throughout the war along with bomber escort missions. In August 1942 fighter operations during the Dieppe Raid were controlled from the Battle of Britain Bunker. In June 1944, fighter operations during Operation Overlord (the D-Day landings) were controlled from the Battle of Britain Bunker by the recently renamed No.11 Group Air Defence of Great Britain.
Post-war: 1945 – 1975
The Battle of Britain Bunker continued as the No.11 Group Operations Room until 1958 when the station was given over from Fighter Command to Technical Training Command. During this time the Ops Room was used to track aircraft during the early days of the Cold War.
In 1958, following the removal of Fighter Command from the station, Lord Dowding (formerly Air Chief Marshal Sir Hugh Dowding during the Battle of Britain) unveiled a memorial close to the entrance to the Battle of Britain Bunker, commemorating its role during the Battle of Britain and the fact that more than two-thirds of enemy aircraft shot down during the Battle were destroyed by No.11 Group. At the bottom of the memorial are recorded Churchill’s famous words: “Never in the field of human conflict was so much owed, by so many, to so few”, first spoken outside the Battle of Britain Bunker on 16th August 1940.