page_title: AI Mk. IV radar
section_title: Baedeker Blitz
hierarchical_section_title: AI Mk. IV radar / Operational use / Baedeker Blitz
caption_attribution_description: English: This spectacular series of six stills was taken from a De Haviland Mosquito NF Mk. II while intercepting a Ju 88 over the Bay of Biscay during bad weather. The fighter was flown by Flight Lieutenant J Singleton with J W Haslam operating the radar, of No. 25 Squadron RAF based at Church Fenton, Yorkshire.
context_page_description: Airborne Interception radar, Mark IV, or AI Mk. IV for short, was the world's first operational air-to-air radar system. Early Mk. III units appeared in July 1940 on converted Bristol Blenheim light bombers, while the definitive Mk. IV reached widespread availability on the Bristol Beaufighter heavy fighter by early 1941. On the Beaufighter, the Mk. IV arguably played a role in ending the Blitz, the Luftwaffe's night bombing campaign of late 1940 and early 1941.
  Early development was prompted by a 1936 memo of Henry Tizard on the topic of night fighting. The memo was sent to Robert Watt, director of the radar research efforts, who agreed to allow physicist Edward George "Taffy" Bowen to form a team to study the problem of air interception. The team had a test bed system in flights later that year, but progress was delayed for four years by emergency relocations, three abandoned production designs, and Bowen's increasingly adversarial relationship with Watt's replacement, Albert Percival Rowe. Ultimately, Bowen was forced from the team just as the system was finally maturing.
  The Mk.
context_section_description: Arthur Harris was appointed Air Officer Commanding-in-Chief of RAF Bomber Command on 22 February 1942, and immediately set about implementing his plan to destroy Germany through dehousing. As part of their move to area attacks, on the night of 28 March a force dropped explosives and incendiaries on Lübeck, causing massive damage. Adolf Hitler and other Nazi leaders were enraged, and ordered retaliation.
  On the night of 23 April 1942, a small raid was made against Exeter, followed the next day by a pronouncement by Gustaf Braun von Stumm that they would destroy every location found in the Baedeker tourist guides that was awarded three stars. Raids of ever-increasing size followed over the next week, in what became known in the UK as the Baedeker Blitz. This first series of raids ended in early May. When Cologne was greatly damaged during the first 1,000-bomber raid, the Luftwaffe returned for another week of raids between 31 May to 6 June.
  The first raids came as a surprise and were met by ineffective responses. On the first raid a Beaufighter from 604 Squadron shot down a single bomber, while the next three raids resulted in no kills, and the next a single kill again. But as the pattern of the attacks grew more obvious—short attacks against smaller coastal cities—the defense responded. Four bombers were shot down on the night of 3/4 May, two more on 7/8th, one on 18th, two on the 23rd. The Luftwaffe changed their tactics as well; their bombers would approach at low altitude, climb to spot the target, and then dive again after releasing their bombs. This meant that interceptions with the Mk. IV were possible only during the bomb run.
  In the end, the Baedeker raids failed to cause any reduction in the RAF's raids over Germany. Civilian losses were considerable, with 1,637 killed, 1,760 injured, and 50,000 homes destroyed or damaged. In comparison to The Blitz this was relatively minor; 30,000 civilians were killed and 50,000 injured by the end of that campaign. Luftwaffe losses were 40 bombers and 150 aircrew. Although the night fighters were not particularly successful, accounting for perhaps 22 aircraft from late April to the end of June, their shortcomings were on the way to being addressed.
caption: Night fighters were used in bad weather, and were sometimes known as night/all-weather fighters for this reason. This sequence shows a Ju 88 being shot down in bad weather by a Mk. IV-equipped Mosquito NF Mk. II over the Bay of Biscay.
exif: {}