One of the most controversial chapters in World War Two reached a turning point this week 70 years ago as Britain’s Strategic Bomber Offensive achieved a technological milestone that would lead to the incineration of German cities and the death of thousands of civilians.

 On the night of March 13, 1942, the RAF launched a successful attack against Cologne with 135 aircraft. While a relatively small force compared to later in the war, the raid was noteworthy for a technological breakthrough: for the first time, the RAF successfully deployed a secret weapon, the Gee navigation system.

 Gee was essentially an electronic beam that created a grid pattern (hence the name ‘gee’) for more accurate night navigation.  This increased the RAF’s ability to find and hit targets with a greater degree of consistency.

Before the advent of more sophisticated navigation systems, the RAF was forced to improvise.

Daylight bombing raids by the RAF in the opening days of World War Two had proved disastrous. In December 1939, a daylight attack by three Vickers Wellington squadrons against naval targets in the Heligoland Bight, located in the North Sea area near the Elbe River in Northern Germany, ended with 15 out of 22 aircraft shot down.

This single raid over-turned the RAF’s prewar doctrine of bomber supremacy. Air strategists had assumed that ‘the bomber would always get through’, an assumption that proved largely false. Losses on the scale of Heligoland Bight were unacceptable.

The only solution was night bombing. But night navigation was perilous. Using wind calculations and magnetic compass triangulation proved haphazard as bomber crews battled the elements and German air defenses.

Most bombers missed their targets by miles. Precision bombing at night was an oxymoron. Without some kind of technological improvement, it was nearly impossible to locate blacked out enemy cities.

Gee was the first serious attempt to solve the problem. By transmitting pulsed radio signals approximately 250 miles across occupied Europe, Gee-equipped bombers were able to calculate their positions using a small cathode ray receiving device installed inside the aircraft matched to the navigators chart.

Although tested previously, the first real operational use of Gee was against the city of Essen. On the night of March 8/9, 211 bombers attacked the industrial town hoping to destroy the famous Krupp factory. But Gee’s debut was disappointing. Poor visibility handicapped RAF bombardiers. Only a few houses and a church were destroyed along with 10 civilians killed. 

Still Bomber Command determined that overall accuracy had improved significantly during the Essen attack.

Less than a week later, the RAF attacked Cologne on the night of March 13/14 with 135 aircraft. The city was illuminated with flares and incendiaries by a handful of Gee-equipped pathfinders. The remaining force hit Cologne’s center starting 237 fires and killing 62 civilians. Only one aircraft was lost.

Bomber Command declared the raid an unqualified success and claimed the Gee-led attack was five times more accurate than previous bombings

Cologne was a tipping point in the Strategic Bomber Offensive. Air Marshall Sir Arthur Harris, the determined head of RAF Bomber Command, would choose the medieval city again as the target for Operation Millennium, the first 1,000 plane raid ever launched.

This time the raid would start over 2,000 fires as the RAF dropped 1,455 tons of bombs, mostly incendiaries on the night of May 30/31, 1942. It was the first time the RAF came close to creating the kind of firestorm that would burn out Hamburg a year later in 1943.  About 400 civilians were killed, another 45,000 were “de-housed”, and 150,000 evacuated the city. The RAF lost 43 aircraft.

Gee was an essential aid. Without it, Bomber Command would never have attempted deploying such a large number of aircraft over a single target, thereby developing the famous “bomber stream” tactics designed to overwhelm German air defenses.

Gee was also an innovation that allowed the Bomber Offensive to evolve into ever greater levels of ferocity, where the mass bombardment of civilians was deemed acceptable to Allied leaders. As such, the Strategic Bomber Offensive remains a contentious and much-debated subject to this day.  

Vickers Wellington
Credit: Wikipedia Commons
Bomber Command's Theatre of Operations
Credit: Wikipedia Commons
Rare comtemporary photo of Gee navigation device