"Culture, technology and war are so interdependent that it is hard to say which drives which. War pushes ahead the development of technology but it also adapts what is already there. The ancient world used levers for their wine and olive presses; the Romans adapted those to hurl stones against enemy soldiers, ships and fortifications. In the Middle Ages craftsmen learned how to make high-quality metal for casting church bells and that then helped in the making of better guns. In the nineteenth century the Swedish chemist and businessman Alfred Nobel invented dynamite for use in mining; it was rapidly adapted to produce a whole range of increasingly effective guns. Farmers in America used barbed wire to pen in their cattle; strung out in front of the trenches in the First World War, it contributed greatly to the power of the defence. The tank incorporated the caterpillar treads which had been developed for tractors. Albert Einstein and his fellow physicists had worked out the theory of how to split the atom, proving on paper that doing so would release a huge surge of energy, but no way of finally testing that hypothesis existed until the Second World War. In their search for victory in the monumental struggle against their enemies, the British and, in particular, the Americans found the resources to refine the necessary uranium and to build and test the first successful bomb. The Manhattan Project, it is estimated, cost over $20 billion, not far short of what the United States spent on all its small arms over the duration of the war"