The Thousand-bomber Raid on Cologne in 1942


Mark Cartwright
published on 28 March 2024

Cologne (Köln) was the first German city to experience a "1,000-bomber raid" by the Royal Air Force during the Second World War (1939-45). The attack took place on the night of 30 May 1942 and was planned as a demonstration of the destruction a large force could do using the strategy of area bombing over a short space of time.

Bombing Raid on Cologne, 1942
Bombing Raid on Cologne, 1942
W. Krogman (Public Domain)

Area Bombing

The Commander-in-chief of RAF Bomber Command from February 1942 to the end of the Second World War was Arthur Harris (1892-1984), and he had very definite ideas on the best and quickest way to win the conflict. Harris, and it should be noted others in high command, including Prime Minister Winston Churchill (l. 1874-1965), believed that extensive and sustained area bombing (aka carpet bombing) – that is, bombing a large area simultaneously – conducted against Germany's most important cities might bring about a surrender without the necessity of a land attack. It was hoped that civilian morale would be severely affected, negatively in the case of the German people and positively in the case of the British, especially after the bombing campaigns already suffered by British cities and the London Blitz in 1940 and 1941. Another motive was to take the war directly to Germany when a land assault was still out of the question.

Remove Ads

From his own experience of the London Blitz, Harris believed that the dropping of incendiary bombs rather than using explosive bombs alone could best wreck a city. A very large force of bombers would be required for what Harris had in mind. Previous operations had shown that daytime bombing brought too heavy losses to the bombers from attacks by fighter planes and anti-aircraft guns. Cloud cover was another impediment to accurate bombing. Switching to night-time bombing had become necessary since the bombers were then much more difficult to find, although this also made bombing even more inaccurate than it already was. Hitting strategic but relatively small targets, like armaments factories or U-boat bases, proved unsuccessful with the technology available at the time. Post-raid reconnaissance revealed that only one in three aircraft dropped its bombs within 5 miles (8 km) of the intended target. The answer seemed to be area bombing. At the time, Britain desperately needed to show that a bombing campaign could cause Germany's war effort serious damage since US President Franklin D. Roosevelt (1933-1945) was just then considering reducing the aircraft he supplied to Britain.

It was far from easy for the RAF to gather together 1,000 aircraft for a single mission.

The Attack Strategy

Harris wanted to assemble a force of 1,000 bombers, the Thousand Plan. He explained that "One of the main ideas of sending over the bigger attack was to overwhelm the defences, and that's exactly what occurred" (Holmes, 299). Statistics support Harris since large bomber forces did suffer fewer casualties proportionally than smaller forces. The German defences included not only anti-aircraft guns but also patrol fighter planes spread out across Northern Europe in the Kammhuber Line and Raumnachtjagd systems. Each fighter plane circled within an imaginary box on a radar grid until it was directed towards an approaching enemy. The system was effective, particularly against RAF bombers which typically approached their target in separate groups. Harris had the idea that by assembling the bombers at a pre-arranged place in the sky and then have them approach the target en masse in a formation known as a bomber stream, far fewer fighter "boxes" would have to be crossed and the sheer number of bombers would mean the fighters would not have time to attack all of them.

Remove Ads

Air Chief Marshal Arthur 'Bomber' Harris
Air Chief Marshal Arthur 'Bomber' Harris
Flying Officer Stannus (Public Domain)

In the spring of 1942, the first large-scale bombing raids, using around 300 bombers each, successfully hit Lübeck and Rostock. Harris, with the approval of Churchill, now organised an even bigger raid for Hamburg for the night of 30 May 1942 when he could finally test his Thousand Plan. However, poor visibility due to the local weather conditions led to a change of target, one which had always been selected as a reserve. Cologne, then Germany's fourth largest city, was to be the objective. Hamburg would be brutally hit in Operation Gomorrah the following year. Cologne was strategically less vital to the German war machine than Hamburg, but it did have important railway marshalling yards and several hundred air-defence factories.

The scale of the devastation came as a shock, even to the German High Command.

In all, around 1,050 bombers headed for Cologne. Far more than a military operation, "it was a propaganda exercise designed to catch headlines and see off Bomber Command's critics in Parliament and at the Admiralty" (Neillands, 119). This was Harris' big test. It was far from easy to gather such a number of aircraft for a single mission, as explained here by Group Captain 'Hamish' Mahaddie: "Harris devised this 'Thousand Plan' - he scraped up a thousand aircraft, not only from his command but he begged and borrowed them from every command" (Holmes, 298). Given that in any operation a certain number of planes would experience technical problems or meet with an accident, Harris managed to muster together 1,086 aircraft for the operation. Then Coastal Command, without giving any official reason, withdrew its 250-plane contribution to the mission.

Remove Ads

Harris' force was now short by a couple of hundred aircraft, and so he was obliged to make up the numbers with training crews. This was a risk since the greatest danger to flight crews came in their first five missions. It was also risky to use inexperienced crews for the bomber stream formation, about to be put into practice for the first time. But Harris did manage to get his force above four figures. The bomber stream was a tight formation but still covered a length of 70 miles (112 km) and a depth of 4,000 feet (1,200 m) – the staggered height was to reduce the chance of mid-air collisions. The raid would be a quick one, with all crews expected to drop their bombs in a total attack period of 90 minutes, the bombers operating in waves of three-minute intervals over Cologne.

Vickers Wellington Mk II
Vickers Wellington Mk II
UK Government Photographer (Public Domain)

The Bombers

The RAF's best and brand new bomber, still relatively few in number at this stage of the war, was the four-engine Lancaster bomber, capable of carrying a bomb load of up to 14,000 lbs (6,350 kg). Other bombers included the Vickers Wellington, a well-designed aircraft whose combination of canvas and steel framework allowed it to withstand tremendous punishment from enemy fire. 599 Wellington bombers took part in the Cologne raid, each carrying a bomb load of 4,500 lb (2,041 kg). The Short Stirling and Handley Page Halifax were also employed at Cologne. These four-engine long-range planes could carry a bomb load only slightly less than the Lancaster. Some of the newer bombers were equipped with Gee radar equipment, which could help them find the target. In order to help the non-Gee-equipped bombers, the Gee-equipped ones would go in first and drop flares to mark the target.

The bombers were to drop a deadly combination of massive 'cookie' bombs and thousands of small incendiary bombs. The former were designed to first smash through the roofs and floors of buildings, and the latter were then dropped to fall deep into the debris, setting it aflame.

Remove Ads

Douglas Mourton, a wireless operator, describes the bomber run to Cologne:

We took off at 2340 hrs and flew across the North Sea to the vicinity of Cologne. I plugged in the intercom and, although I could hear shrapnel hitting the side of the aircraft, there was no conversation among the crew…we were flying along straight and level with flak bursting on our port side…also there were Lancasters and Halifaxes about, and to hear a big rumble and be rocked by a passing four-engined bomber or take the risk of being hit by bombs falling from above was very stressful.

(Neillands, 122)

Cologne Bomb Damage, 1942
Cologne Bomb Damage, 1942
Australian War Memorial (Public Domain)

Damage & Death Toll

By the time the bomber force had reached Cologne, it had been reduced to around 900 aircraft. They dropped 1,455 tons of bombs on the city, about two-thirds of which were incendiary bombs. Cologne, outside the small historical centre, had many wide streets, and this helped contain fires to individual blocks and prevent the creation of a firestorm, as happened the next year in Hamburg. Nevertheless, the city's firefighters could not cope with so many incendiary bombs dropped from so many planes in such a short period of time.

Frau Chantrain of the Cologne Red Cross gives the following description of the carnage:

When the sirens sounded everyone went into the air-raid shelters and it was a short attack. The sirens sounded about ten o'clock and in half an hour Cologne lay practically in ruins - I came out of the air-raid shelter and Cologne was a wall of flames. I tried to get to my station but it was very difficult to reach it because Cologne was built with pretty narrow streets and the balconies were on fire and falling in the streets. The digging parties hauled the dead people out and laid them at the side of the road. Those who had been killed by high-explosive bombs were propped up, their skin was grey, pallid colour and their hair stood off their heads like wire nails. And of those who had died of incendiaries you could only find bits of bone, which were gathered up in washtubs, big zinc baths. The cruellest thing was when you had a friend in these houses; you saw bones lying there or you knew they were underneath. That was unbelievably horrible. Mothers came to me who had themselves very severe burns who were scarcely capable of life, with their children in their arms, and begged for help. We saw it was pointless - the children were beyond help. The soldiers on leave from the front came and asked after their relatives and you had to tell them they are dead – your wife is dead, your children are dead, your grandparents are dead.

(Holmes, 300)

Bomb-devastated Cologne
Bomb-devastated Cologne
US Department of Defense (Public Domain)

The scale of the devastation came as a shock, even to the German high command. Field Marshall Hermann Göring (1893-1946), head of the Luftwaffe, refused to believe the reports coming in from officials in Cologne as to the number of bombers involved, the amount of bombs dropped on the city, the extent of the damage, and the casualties sustained. Over 15,000 buildings had been destroyed or damaged, including 1,500 factories. The city's networks of electricity, gas, and water supplies, and various transport networks were all severely damaged. It took a week for the fires to die down sufficiently for the RAF reconnaissance planes to take photographs to properly assess the damage done.

Miraculously the city's cathedral survived the onslaught despite being located in the heart of old Cologne centre, which was identified as the RAF's official Aiming Point (AP) for the raid. This perhaps illustrates just how inexact bombing was at the time, but the cathedral's escape was also due to the typical bombing strategy where each successive wave dropped bombs slightly before or after the previous drop, spreading out the destruction in ever-wider circles. For this reason, it was said that the best chance of surviving a bombing raid was to stay in an air-raid shelter right under the AP since only the first few bombers struck there, and they would probably miss.

Remove Ads

The Cologne Police report noted that over 45,000 people had been made homeless overnight. Fortunately, after being warned 30 minutes before the bombers arrived, the vast majority of people had taken to the city's air-raid shelters or the cellars of their own buildings. According to the official police report, there were 469 people killed and around 5,000 injured. The RAF losses were deemed acceptable: 41 planes lost. Around half of the losses were a result of enemy fighter attacks when either getting to or returning from Cologne. Two pairs of planes were lost after colliding with each other over the target area. The bright moonlight had certainly helped the pilots avoid the chaotic jumble of flying machines despite some disobeying orders and touring the city's skies to see the damage they had wrought.

Lancaster Dropping Bombs
Lancaster Dropping Bombs
Unknown Photographer (Public Domain)


The British regarded Cologne as a success and continued the strategy of area bombing on other German cities like Bremen, Düsseldorf, Essen, Hamburg, and Berlin. Cologne was bombed heavily again later in the war while one of the most controversial raids was the bombing of Dresden in 1945.

The strain on resources such large operations required meant the 1,000-bomber raids could only be used intermittently. In addition, area bombing remained a contentious issue for the number of civilian casualties it caused, and there was still much debate as to its strategic value. Morale and cities were badly beaten but not smashed. Usually, repairs were made and normal operations resumed within a matter of months. Even if civilian morale had been broken, in a totalitarian state built on violence, there was not much anyone could do to influence policy change. The delays between raids meant people had time to recover both physically and mentally. As the German Minister of Armaments Albert Speer (1905-81) noted, "If you would have done with one stroke, very heavy bombing, then possibly the result on our morale would have been heavier" (Holmes, 298).

Love History?

Sign up for our free weekly email newsletter!

Many military leaders preferred the strategy of precision bombing strategically important targets, like armaments factories. Such targets were, though, well-defended and difficult to hit. The bombing of cities did divert a vast amount of resources into their defence which might otherwise have been used elsewhere. Speer noted that "in the western theatres of war ten thousand anti-aircraft guns were pointed toward the sky…the anti-aircraft force tied down hundreds of thousands of young soldiers" (381-2).

In the end, both the RAF and United States Air Force (USAAF), in what became known as the Combined Bomber Offensive, carried out both types of bombing raids for the remainder of the war which only ended with the ultimate of area bombing raids, the atomic bomb drops on Hiroshima and Nagasaki in Japan.

Did you like this article?
Editorial Review This article has been reviewed by our editorial team before publication to ensure accuracy, reliability and adherence to academic standards in accordance with our editorial policy.
Remove Ads

About the Author

Mark Cartwright
Mark is a full-time author, researcher, historian, and editor. Special interests include art, architecture, and discovering the ideas that all civilizations share. He holds an MA in Political Philosophy and is the WHE Publishing Director.


We want people all over the world to learn about history. Help us and translate this article into another language!

Questions & Answers

Why was Cologne bombed in World War 2?

Cologne was bombed in World War 2 as a test of the strategy to use 1,000 bombers to completely smash a city and civilian morale. The RAF deemed the raid a success, but its strategic value remains debatable.

How many bombers attacked Cologne?

Over 1,000 RAF bombers set off to bomb Cologne in May 1942, but due to mechanical failures and losses to enemy attacks on the way, only around 900 made it to drop their loads over the city.

Was the thousand-bomber raid on Cologne a success?

For the RAF, the 1,000-bomber raid on Cologne in 1942 was a success since it shocked the enemy, destroyed the city, and led to Germany investing many more resources and men into air defences. The loss of 41 planes in the operation was deemed an acceptable percentage, and more such raids were carried out during WWII.

Free for the World, Supported by You

World History Encyclopedia is a non-profit organization. For only $5 per month you can become a member and support our mission to engage people with cultural heritage and to improve history education worldwide.

Become a Member  

Recommended Books

Sorry, we haven't been able to find any books on the subject.

Cite This Work

APA Style

Cartwright, M. (2024, March 28). The Thousand-bomber Raid on Cologne in 1942. World History Encyclopedia. Retrieved from

Chicago Style

Cartwright, Mark. "The Thousand-bomber Raid on Cologne in 1942." World History Encyclopedia. Last modified March 28, 2024.

MLA Style

Cartwright, Mark. "The Thousand-bomber Raid on Cologne in 1942." World History Encyclopedia. World History Encyclopedia, 28 Mar 2024. Web. 31 Mar 2024.