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There were four main types of British bomber in use at this stage of the war. The newest and most effective was the Avro Lancaster: a huge, sleek machine capable of flying to Berlin and back laden with over six tons of bombs. Its long, cigar-shaped fuselage was punctuated by five Perspex blisters, through which its crew would constantly scan the skies for attackers. Four Rolls-Royce Merlin engines along its wings could carry it to a height of 22,000 feet and above, and at speeds of 266 m.p.h. The Lancaster was unquestionably the best night bomber of the Second World War.
Slightly bigger and more temperamental in the air was the Handley Page Halifax. With a ceiling of 20,000 feet, the Halifax was relatively safe from flak, but its blind spot beneath the back of the aircraft made it vulnerable to fighters coming from behind and below. Despite its impressive ceiling, and top speed of over 275 m.p.h., it could carry only just over half the bomb load of a Lancaster.
The Short Stirling was often described as a ‘gentleman’s aircraft’: it was easy to handle, and capable of absorbing an enormous amount of punishment before it succumbed to flak or fighter fire. Without the waist-high spars that the Lancaster had in its interior, it was also relatively easy to escape from – which was fortunate, because its lamentable ceiling of only 16,000 feet made it the first target of all the German flak batteries. There are tales of Lancaster and Halifax crews cheering when they heard that Stirlings would be accompanying them on an operation, because they drew German fire away from the higher-flying machines.
The last type of aeroplane that flew to Hamburg that night was the twin-engined medium bomber, the Vickers Wellington. This unfortunate aircraft was virtually obsolete by this stage in the war, and seemed to combine all the worst drawbacks of all the four-engined ‘heavies’. It was slower, smaller, and had fewer guns to defend itself. It flew at a similar height to the Stirling, but could carry less than half its bomb load. Seventy-three of these aeroplanes had taken off for Hamburg that evening, with a further twelve tasked with minelaying in the Elbe estuary and dropping propaganda leaflets over France.
For the first part of the trip, the main force would also be accompanied by a small force of light bombers: eleven De Havilland Mosquitos would follow them across the North Sea, then peel off to attack alternative targets in Kiel, Lübeck, Bremen and Duisburg. These additional targets were merely diversions, designed to keep the Germans guessing about the main force’s true destination.
At first glance such diversionary missions looked extremely dangerous for the crews concerned: bombers are like herd animals – safe in numbers but vulnerable when they venture out alone. If one considers that the Mosquito was made only of plywood, and usually had no defensive armament, then those four diversionary raids looked like a suicide mission. However, Mosquitos were so fast, and capable of flying at such extreme altitudes, that they were virtually untouchable. All would return unscathed to England the next morning.
This, then, was the force that took off from airfields across England on 24 July. Its first task was to climb as high and as quickly as possible – the higher they were, the safer. As they did so, they set course for their crossing points on the English coast: 4 Group and the Canadians of 6 Group headed towards Hornsea, 1 and 5 Groups made for Mablethorpe, on the coast of Lincolnshire, while 3 Group and the Pathfinders of 8 Group headed for Cromer, in Norfolk.
Over those seaside towns all the separate squadrons in each group would merge into a wide stream heading out to sea. For those in the vanguard it was possible to make out many of the other aircraft filling the sky around them. By now it was well after ten o’clock, but with double summertime bringing the clocks forward two hours the sky was still fairly light, especially to the north and west. For those coming later it was already too dark to make out any of their fellow aeroplanes. Only the occasional blink of green and red navigation lights told them that they were not alone, but as they headed out to sea even those lights were extinguished, rendering almost eight hundred aircraft virtually invisible in the night.
As they made for the darkness of mainland Europe, the atmosphere inside each aeroplane was professional, businesslike. Each member of the crew was left to perform his duties in his own way. In general, strict radio silence was observed, and crews did not speak to each other on the intercoms unless there was something important to report. The only sound was the constant drone of the aircraft engines as they continued to climb as high as they could go, but in the thin, warm air of summer many aeroplanes struggled to reach their operational ceilings.
Leading the bomber stream were the Pathfinders of 8 Group. Behind them, spreading back over almost two hundred miles, was the rest of the force. They were heading to a point about eighty miles from the German coast – 54°45N, 07°00E – where the three separate streams of bombers were to merge into one, then turn towards the south-east and their target. The lead aircraft had already been in the air for two and a half hours. They turned at about twenty past midnight and headed towards the German coast on a bearing of 103°.
Ten minutes later the flight engineer in each of the leading aircraft climbed over the main spar into the back of the plane and began to drop the first bundles of Window. 10The crews had been provided with stop watches and told to throw the bundles down the flare chute at exactly one-minute intervals. The bundles were supposed to disperse into small clouds of paper that would float harmlessly down through the air. In practice, however, the ‘machine-like’ efficiency called for at the briefing often ended up being a little more chaotic. Sometimes the Window would blow back into the aircraft, filling the air in the back of the plane with metallized paper strips. Once or twice the bundles did not open properly and the solid packets hit other bombers, ripping off aerials or even breaking through the Perspex of a gun turret. 11Even when the Window dispersed properly, it often blew up on to the mid-upper turrets of the aeroplanes, obscuring the gunner’s view. One side of the paper was covered with a black coating that easily rubbed off, and after fifteen minutes or so the plexiglass on the mid-upper turret was so smudged and blackened that the gunner there was effectively blinded. The black coating also came off on the man tasked with throwing it from the plane; many bombaimers and flight engineers soon looked like chimney sweeps, covered from head to toe with soot.
Despite the various mishaps, though, most of the crews managed to drop the bundles of metal strips according to plan. As they ploughed on towards the German coast they had no idea whether or not the new device would work, and gradually they became anxious once more. In less than half an hour they would be over Hamburg, and the real test of their new tactics would begin.
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By now the Germans knew the RAF were coming. A long-range Freya radar station near Ostend had picked up the first aeroplanes heading across the sea at around eleven o’clock, and the defences had been plotting the course of the bomber stream ever since, waiting to see where it turned before committing their night fighters to action. 12By half past midnight, shortly after the first planes in the bomber stream had turned towards Hamburg, the night fighters of several airfields were airborne. Since Hamburg was now a possible target, at 12.33 a.m. the order was given to sound the Fliegeralarm sirens. 13
In 1943 Germany had the most impressive defences of any country in the world. First came the infamous Kammhuber Line – a belt of interlinked night-fighter ‘boxes’ that stretched the length of the European coast. Each box had its own fighters, which would patrol that box only, ensuring an evenly spread defence across the whole line. Hamburg in particular was protected by more than a dozen airfields. 14Closer in, there were belts of searchlights, and dozens of heavy-flak batteries (see Map 1, p. 36). It was a formidable set-up, and the whole structure was now on high alert, waiting for the British to arrive.