The Battle of Britain's 'hardest day' https://www.nationalarchives.gov.uk/explore-the-collection/explore-by-time-period/second-world-war/the-battle-of-britains-hardest-day/
The Battle of Britain's 'hardest day'In 1940 the Royal Air Force resisted major aerial attacks from Germany in what became known as the Battle of Britain. On 18 August, sometimes called the ‘hardest day’ of the fighting, many sites in southern England were targeted. One of them was Kenley, a fighter airfield just south of London.