Routed to the target over the north coast of Holland and Germany, crews avoided the Kammhuber line and the night-fighter threat on mining operations. On the other hand, when flying at such low altitudes, they were highly vulnerable to shore-based and ship-borne anti-aircraft batteries guarding the waters the Germans expected the British to mine. And crews were instructed to be absolutely certain to find the right location to deposit the mine, or bring it back, and it was not uncommon for them to fly around for up to an hour to pinpoint the location, all the while exposed to anti-aircraft fire from close quarters. On release, crews would see only a splash, if cloud and fog permitted, never an explosion.
RAF jargon for mine-laying was “gardening.” Crews were instructed to plant their vegetable, and enemy coastal waters were divided into areas with code-names such as “forget-me-not” (Kiel Canal), “nectarine” (Frisian Islands), “onions” (Oslo), or “artichoke” (Lorient). Hampden crews on mine-laying sorties were also equipped with 250-pound wing bombs, and were expected to use these and their machine guns to attack enemy ships as the opportunity arose, after dropping their vegetables.
In an ebullient mood, he decided to buy a bicycle, or, as he told Janine,
Roger decided I should buy a bike since he had to drive me everywhere on his handlebars. Our other pal, Dave Davies, our honest Welsh pal rides his landlady’s 1890 model about so I took the plunge and bought one from the local dealer – a second hand one to be sure – but a magnificent machine we all agreed.
By way of celebrating we drove to the nearby village of Horncastle and whilst polishing off the odd half dozen in a pub my lamp was stolen. We were exceedingly annoyed – yes they were all in a condition to take my loss to heart. Suddenly a copper – known as a bobby in these parts, stopped me and hauled me out for not having a lamp. Despite the fact that I always have had an extreme distaste – in fact wholesome dislike for the so called enforcers of law and order – I politely tried to explain why I was riding in their lovely town by the light of a full moon, with three hundred yards visibility, in a village devoid of life and traffic without a lamp. He was bone and bull-headed enough to remain unconvinced. By this time the three of us had four constables, one sergeant police and the chief to deal with – we put up with as much as our exuberant spirits would allow and then gave them a solid telling off. But when I told them to get some Ruhr hours in over Germany – they really blew up and tried to bring up their war record – then the fun began – a wordy battle ensued and the flying Canucks left their names in the police records and their words of wisdom firmly implanted in their desolate heads.
But now for the bike. The tires on my magnificent bike were flat and after putting three patches in the back tire it was still leaking like a sieve – well we struggled home. Next day I bought a new tube. Roger insisted on putting it on quickly – he did but it still would not blow up – he ripped it putting it on so we had to patch a brand new tube up. I at last rode my magnificent bike for the first time to-day. It took me so long to get in that I missed dinner to-day but it is a lovely looking bike, and should be very handy once it gets used to me – so the moral of this long winded story is – beware of bikes – mine cost me four pounds – a police record – a lost meal and I am still frightened to breathe hard for fear of putting too much stress on it. (JJL 4 September 1941)
Joe kept his notice of fine in the amount of ten shillings, issued by the Petty Sessional Division of Horncastle, as a souvenir of his encounter with the authorities.
Joe’s objectives, showing distance from RAF Coningsby, and the location of the Kammhuber Line. (Map created by Mike Bechthold)
Twenty
The Four Horsemen
Sooner or later, every aircrew would be confronted by the four horsemen of their apocalypse: unpredicted weather, icing, anti-aircraft artillery, and night-fighters. Any one or more of them could be encountered on any sortie over Germany, and any of them could be fatal. Joe Jacobson gained experience of all four during his first month on operations.
The ideal conditions for finding the target were clear skies and a full moon, but these were also the ideal conditions for the German defences to find the bombers. Partial cloud cover, especially low cumulus cloud, provided bombers intermittent cover from anti-aircraft gunners and night-fighters, but also made their targets more difficult to find.
Exceptionally low temperatures at altitude could impair aircraft function and subject crews to mind-numbing cold and even frostbite. Unpredicted changes in wind direction and speed could send an aircraft off-course or delay its return to base to the point of running out of fuel. On cold mornings, fog creeping in from the Lincolnshire fens could completely obscure aerodromes when returning aircraft were running low on fuel and their crews fatigued by the stress of battle.
It was the heavy cumulonimbus clouds associated with advancing weather fronts, however, that signalled the worst hazards: turbulence, violent updrafts or downdrafts, electrical discharge, and icing. And in those days, the normal operating heights of bomber aircraft corresponded to the layers of those storm clouds at which those hazards were at their worst. Those conditions were common over the North Sea in winter with cold air above the sea, and in summer over the Continent with warm air rising into cold. Crews encountering these situations early but unable to overcome them could abort their sortie, but on return, they could only hold tight and hope for the best.
Meteorology in those days could not reliably forecast weather conditions over Europe twelve hours ahead of a bombing operation, or even over England eighteen hours ahead when the bombers would be returning. Meteorological readings were no longer shared among nations in wartime; weather forecasts became military secrets, no longer released to the public. Britain had the advantage of access to weather data from Iceland, Greenland, and ships in the Atlantic. But with no direct observations from Europe, weather maps of the Continent could only be projected based on known meteorological principles. Regular meteorological reconnaissance flights over Germany were yet to come. It was difficult to predict how quickly fronts would move in from the west, or whether fog would form the next morning. Forecasting cloud cover and height, and wind speed and direction at various altitudes, that might be encountered along specific routes and in target areas was especially problematic. So each morning, Bomber Command planned its nightly operations on a best guess about the weather, and navigators soon learned to take the information they were given in afternoon briefings with a grain of salt.
Of all the natural hazards crews encountered in the air, the worst was the second horseman: icing. Icing occurs when an aircraft enters dense cloud at subfreezing temperatures, and most dangerously when it encounters a temperature inversion in which rain falls through freezing air. This rain accretes on the surface of the aircraft as hard, clear ice, weighing it down and impairing the lift capability of its wings and the responsiveness of its controls. Ice accumulation can plug up the external airspeed indicator, damage the wireless mast, and obscure visibility through windscreens. Even engine performance is at risk if ice forms in the carburetors. An extremely hazardous and uncontrollable situation can develop within in minutes, to the point of unrecoverable stall or spin, forcing an aircraft down.
Preflight meteorological forecasts of air temperatures aloft, and visible signs of potential icing conditions – storm clouds associated with cold fronts – warn of dangerous conditions ahead. Civilian pilots are instructed to avoid them, but bomber pilots heading to a target on schedule must press on as best they can. The summer icing associated with cumulonimbus storm clouds that Joe encountered on the Hanover operation is normally sporadic, and may be easier to avoid by going around the worst concentrations, or to escape by rapid ascent or descent. With luck, the ice sloughs off without damage and nothing is lost except a little extra fuel supply. In more severe and pervasive conditions, most likely to be encountered in winter as warm, wet air associated with an incoming warm front rises over cold air below, there may be no safe altitude except above th
e cloud formation altogether, and reaching that was beyond the capability of most aircraft and most crews. But descending into colder, dryer air will not necessarily solve the problem if the ice is too dense to shake off.
The problem of icing was well known, and more than a few Hampden crews had been forced to deal with it in previous months. Inflight de-icing mechanisms, notably movable de-icing boots installed on the wing’s leading edge, had been developed in the United States many years before, but this was yet another technology not applied to bomber aircraft in Britain, most likely because the additional weight would have reduced performance and payload. There had been experience with applying de-icing compound to the wings before takeoff, but the benefits were short-lived. Of all the hazardous weather conditions that might confront a bomber crew, forecasting ice conditions in cloud was especially problematic. Crews were instructed in tactics to deal with icing, but few gained sufficient operational experience to get good at them. Pilots had to be lucky to survive their first encounters.
The other two horsemen of the apocalypse were of human creation. They were the enemy’s defences: anti-aircraft artillery and night-fighters. Germany defended itself against night bombing with radar, searchlights, and anti-aircraft guns on the ground, and night-fighters in the air. None of these was new, but by early 1941 the Luftwaffe had not only increased the quantity and capabilities of each, it had figured out how to combine them into an integrated barrier stretching all the way from Denmark to France.
The first line of defence was the chain of radar stations along the North Sea coast that warned of approaching aircraft. About a hundred miles inland, through eastern Holland and Belgium, there ran a line of night-fighter bases and searchlight arrays from Denmark to the Rhine through eastern Holland and Belgium, along with a second line of radar, the so-called Kammhuber Line. The Luftwaffe divided this line into sectors or boxes about twenty kilometres deep, and assigned one night-fighter to each. As soon as an incoming bomber entered the box (which took several minutes to cross), the main searchlight sought it out, the rest of the battery coned it, and the ground controller guided the night-fighter to it from a central beacon known as Kleine Schraube (Little Screw), within each box. The RAF was still trying to figure out how the system worked. But what crews did know for sure was that searchlights without flak meant you were being hunted by a night-fighter. And Germany’s night-fighters, much faster than the RAF’s lumbering bombers, were now better equipped to hone in on those bombers, except in conditions of heavy cloud. By midsummer of 1941, the night-fighters had the advantage of better weather, clearer skies, and shorter nights with longer periods of twilight against which to spot incoming aircraft. On nights with thick cloud, the night-fighters were grounded, but the anti-aircraft guns could still operate, even if with reduced effectiveness. When Joe Jacobson began operations, there were over a hundred of these night-fighters based in Holland, and they were accounting for over half of Bomber Command’s aircraft shot down.
The third, inner line of defence consisted of searchlights and anti-aircraft artillery batteries placed around the major cities, industries, and military facilities of northwestern Germany, and around Berlin. The searchlights could capture a bomber in an intense, dazzling cone of light, even at three miles up, disorienting its crew and setting it up as a target for anti-aircraft artillery. These guns fired 88 mm shells that rose to that height in ten seconds and exploded into a spray of shrapnel, or flak. A direct hit could take down an aircraft, while an explosion within ten metres or so could cause serious damage and personal injury. Most anti-aircraft shells exploded without effect, but a bomber aircraft’s thin aluminum skin offered little protection to its crew or such vital components as fuel lines, hydraulics, and oil systems. It was common enough for aircraft to return to base with small holes in the fuselage. Once coned, a bomber pilot had to dive and twist to try to escape it and avoid being shot down. By mid-1941, the ability of anti-aircraft batteries to locate their targets was enhanced by on-site radar capable of detecting the speed and track of approaching aircraft. What they lacked in accuracy they more than made up in quantity of fire.
At bomber height, the shell bursts from intense anti-aircraft fire, with dozens of guns firing twenty or more rounds a minute, appeared to oncoming aircraft, and especially to the bomb-aimer surrounded by clear Perspex in the nose, as a curtain of smoke from explosions and light trails from tracer fire. For novice crews, it was an awesome and fearsome gauntlet to have to run on approach to their target. More experienced crews could better judge the hazard and try not to let it distract them from the task at hand.
In combination, the searchlights, anti-aircraft guns, and night-fighters had become a formidable, although not impenetrable barrier, especially in clear weather. It didn’t have to be impenetrable to do its work; it had only to be ruinous enough to deter. In 1940, Bomber Command’s operational losses, running at about 2 percent, had been thought mostly due to bad weather or faulty navigation. Losses to enemy action were attributed very largely to anti-aircraft fire. By August 1941 the operational loss rate was approaching 4 percent, over half of which was attributed to night-fighters.
In 1940, the bombers had been able to operate in the target area for up to an hour to identify their aiming points, and then attack from a few thousand feet up. This was no longer safe practice. Better to fly high, drop one’s bombs as quickly as possible, and get away. Nor could pilots safely maintain straight and level flight on their final approach in the face of such intense opposition from below, so bomb-aiming became less accurate. It took a strong stomach to resist the temptation to bomb short and get the hell out of the zone of most intense danger. So not only was Germany’s air defence system now inflicting punishing losses on bomber crews, it was making accurate bombing nearly impossible.
Bomber Command developed several countermeasures. Flying higher over flak batteries was one, taking indirect routes to skirt the Kammhuber Line was another, penetrating that line at lower heights and greater speed yet another. But whether the existing tactic of each aircraft making its separate way to the target should continue, or instead fly together in a concentrated stream, was a matter of continuing debate. The first was thought to confuse the defences; the second, it was hoped, would overwhelm them. But Bomber Command had neither sufficient numbers of aircraft, nor the techniques to keep them safely separated over the target, to carry out the second tactic successfully. So the first continued.
The old problems of navigation and bomb-aiming at night were compounded in 1941 by Germany’s increasingly effective air defence system. And Bomber Command’s main force still consisted of undersized and underpowered aircraft, in insufficient numbers. So the necessity of area bombing deepened. Crews were told to attack any town or built-up area so as not to waste bombs. And to make those attacks more effective, Bomber Command was developing the means of fire-raising with incendiary bombs.
A month into operations, Joe had satisfied his curiosity about the course he had embarked on and the hazards he might face. Imagination would not help. Raw courage would be needed to confront the four horsemen each night.
Twenty-One
Confidence Tested
Not long after Joe had penned his confident assessment of the bombing campaign to his father, he would have read the August edition of the Navigation Bulletin. Bomber Command issued this mimeographed document of several pages to all its stations for the benefit of air observers. This month’s edition featured a synopsis of a study of fifty recent air photos taken by crews during their bombing raids. Only three of the fifty photographed explosions, it turned out, were within a ten-mile circle around the target. “10 mile errors,” the article concluded, “come into the sphere of navigation and cannot be rectified by the bombing specialists.”1
These were only the barest details of a study – the “Butt Report” – that Bomber Command had received two weeks after Joe had begun operations.2 Night cameras had recently been developed for use on bomber aircraft, but only a few as
yet carried them. Yet, enough photographs – over six hundred – had been taken of the purported target areas in June and July to make the study possible. During that time Bomber Command had dispatched over six thousand sorties, and about two-thirds of their crews had claimed to reach the target area. So these photos amounted to a 15 percent sample of crews supposedly over target. The study method was simple enough. The photos taken of the locations identified by the crews were compared with the known target areas as they appeared in daytime photographs. Less than one-third matched, meaning that the rest of the photos were taken of areas that had been misidentified by the crews.
Target areas, defined generously as a radius of five miles around the aiming point (an area of about seventy-five square miles), reached far beyond the built-up extent of most cities. So even the minority of crews who bombed within the target area did not necessarily do much damage, as their bombs were very likely falling on open countryside. The situation was even worse over the industrial targets of the Ruhr, commonly obscured by ground-level haze and heavily defended by anti-aircraft batteries, and it was especially problematic on moonless nights. The report estimated that in conditions of thick haze and no moon, only one in fifty aircraft had correctly identified the target area.
Very simply, although the great majority of aircrews believed they had succeeded most of the time, they were not seeing what they thought they were seeing, and their bombs were not falling where they believed they had. And as dismal as the report’s findings were, they spoke only to problems of navigation and target-finding. The study was not designed to determine the actual damage caused on the ground by the relatively small proportion of bombs finding their way to the aiming point. That required daytime photo reconnaissance by fighter aircraft.
Joey Jacobson's War Page 24