The second most important thing was the use of high-explosive bombs. Most people assume, instinctively, that the purpose of explosives is to destroy buildings. Our perception is coloured by our modern experience: the bombs used by terrorists, or even by conventional military forces, are almost always designed to cause maximum damage to buildings by razing them to the ground. But bombing during the Second World War was carried out on such a huge scale that different tactics were required. Fire is far more efficient than high-explosive bombs at destroying large areas, so Allied tactics were aimed at getting the fires to spread as far and as quickly as possible. Military planners had learned early in the war that if they wanted their fires to spread it was counter-productive to blast buildings down because this created fire breaks. The purpose of high explosives, therefore, was not to destroybuildings but merely to blow in as many doors and windows as possible, to allow the air to get inside and feed the flames. Buildings that were not yet burning would catch fire as the sparks and embers from neighbouring buildings floated in, setting curtains and furniture alight. By blowing off roofs, high-explosive bombs would also allow the incendiaries to pierce the lower floors of a building, where they could do most damage. The explosions would have the added effect of keeping most fire-fighters inside their shelters long enough for the fires to take hold, and putting craters in the roads that prevented fire engines getting to affected areas. So while the incendiaries would do most damage, high explosives had an essential role, and it was important that the exact mix of the two different types of bombs was right. ¹⁰

One might be tempted to ask what kind of mind comes up with such theories, but to be fair to the Allies a great deal of the research had been done for them – or, rather, tothem. During the Blitz in 1940–41, the Luftwaffe had rained incendiaries on London and other cities, causing huge damage. The British, who had only really used high-explosive bombs until then, soon learned that the fires did far more damage than the explosions, and began to experiment accordingly. ¹¹Repugnant as it might seem now, the cruel logic of war requires such efficiency. By the summer of 1943, RAF planners had brought large-scale bombing to a fine art.

* * *

The concentration of bombs on Hamburg that Tuesday night was so great that the civil-defence organizations in the eastern quarter of the city had little chance of saving anything. ‘After only a quarter of an hour, conditions in these districts were terrible,’ claimed the official German report shortly afterwards. ‘A carpet of bombs of unimaginable density caused almost complete destruction of these districts in a very short time. Extensive portions were transformed in barely half an hour into one sea of flame.’ ¹²The bombs came down so thick and fast it was impossible to stop the spread of fire: tens of thousands of individual fires quickly became one vast conflagration.

The people of Hamburg had been expecting another attack, but nothing could have prepared them for the hammering they were now experiencing, especially in the eastern quarter of the city. Even those who had lived through the first night of attacks must have been shocked at the intensity of tonight’s bombardment. For Fredy Borck, the eleven-year-old who lived in the riverside district of Rothenburgsort, it was the most terrifying night of his life:

Suddenly it started to happen outside. It was a bombardment that is still indescribable, even today… All around us were the crashes of bombs striking with appalling explosions – ear-shattering explosions that seemed to be right next to us, over us. You could even hear the howl of the nearer bombs before they hit, then the crash as they burst. It must have been hell outside! It got worse and worse. The walls of the cellar rose and sank… An inhuman screeching and groaning came from the walls. We screamed along with it, screaming out our terror! We lost all self-control, crouched on the benches, cowering together with our heads between our knees to cover our ears. ¹³

Fifteen-year-old Herbert Wulff was sheltering in a basement in Süderstrasse, right at the centre of the main attack. He was huddling with his mother and sister when the sound of the bombs became unbearable: unlike Fredy Borck, his instinct was to leave the shelter and take his chances outside. His sister was still recovering from a gall-bladder operation – she had been discharged from Barmbek hospital early because the room where she had been recuperating was destroyed in the first night of attacks. Even so, Wulff recalled, she too was determined to get out of the basement shelter:

Shortly after everyone in the building had filled the cellar, the whole building shook, right down to the foundations, from the explosion of a huge bomb. I can still see it, how the foundation walls moved between the buttresses and swayed dangerously. Then the lighting went out abruptly, and a cry rang out through the cellar room, and I thought for a moment that my final hour had come. After that first terrifying second we had only one thought: to get out of there. Instinctively my mother, my sister and I grabbed each other’s hands and pushed our way through to the cellar stairs. ¹⁴

Some people – the foolish and the brave – were already outside their cellars watching events unfold. Most houses and factories had a fire warden who would make regular patrols for incendiaries, and call for help from the shelters when a new fire needed to be put out. ¹⁵Many of those brave men and women died before they had a chance to do anything useful. The survivors found themselves quickly overwhelmed by the sheer numbers of incendiary bombs falling around them. The German authorities estimated that 96,429 stick incendiaries fell on every square kilometre of ground, plus a further 2,733 larger incendiary bombs. This was over five times as concentrated as the previous large-scale attack. ¹⁶To give some idea of what this meant on a human scale, imagine a large attic room, about ten metres long and ten metres wide. On average, in this attic room alone, ten incendiary bombs would fall, each crashing through the ceiling to set the roof timbers alight.

The incendiary bombs were of two main types. The most common were the four-pound thermite stick incendiaries. They fell nose down, to strike roofs so hard that they would either lodge in the roof cavity or pierce through to the rooms below where they would burst into flame. Some were also fitted with an explosive charge, so that if a fire warden came across it in time to shovel it out of a window it would explode, killing or maiming him or her. The second type of incendiary was bigger, weighing thirty pounds, and was heavy enough to crash through the roof space into the lower storeys. They were filled with a liquid mixture of Benzol and rubber, designed to splash across whatever the bomb hit, setting fire to everything within ten metres. German civilians tended to call them, and all incendiaries, ‘phosphor bombs’, which gave rise to a number of gruesome myths. Phosphorus is a particularly evil substance: it sticks to the skin and is impossible to put out as long as it is in contact with the air. In fact, while a small number of bombs contained phosphorus, the vast majority were made from other substances, less immediately terrifying, but much more effective at starting fires. ¹⁷

With dozens of apartments catching fire simultaneously, whole blocks were soon ablaze. Henni Klank, a young mother, was one of those who ventured out of her shelter.

I don’t know why, but suddenly the Devil possessed me; I wanted to go into our house one more time. Perhaps I thought I could still get some things out, like papers, photographs, and such things. But as I stood in the corridor the ceiling was already crackling, and I wanted to go to my father’s desk in the living-room, but there I saw only fire. The blazing and burning curtains flew in the room, the window panes burst and there was a hissing and crashing all around me. I couldn’t manage the few steps to the desk, which stood at the window, my legs felt paralysed. While dashing out of the apartment I hadn’t grabbed even a single article out of the wardrobe. I was in such a panic that I rushed back to the shelter as quickly as possible. The streets were already burning, the firestorm was now raging through all the streets! ¹⁸