The history of Germany and the German-speaking peoples is as complex and multifaceted as any in Europe. It is also one of the most difficult to pinpoint conceptually and historically, since every nation is a construct to some extent. Language is certainly important, and the German language is a unifying factor for any notion of a unified Germany, yet even today, many German-speakers live outside the borders of modern Germany. Shared customs and traditions gave Germans a common sense of identity to some extent, but these were often local in origin. Germans were also split between several versions of Christianity. Nevertheless, ideas of a German nation were present by the 19th century, leading up to the official unification in 1871. Neil MacGregor, a historian of modern Germany, has explained that the two defining events leading to the rise of German nationalism and the movement toward unification were the Thirty Years' War and the Napoleonic Wars.
During the Thirty Years' War, more than 200 German states were part of the Holy Roman Empire's loose confederation, and that war was predominantly fought in German states by foreign powers, including France, Sweden, Denmark, Austria, and the Netherlands. MacGregor noted that "horrors were experienced across all Germany, and were never forgotten," to the extent that they were invoked during World War II. The religious basis of the Thirty Years' War saw the split between Catholicism and Protestantism, which was at the heart of the Reformation. Some foreign leaders even invoked defending "German freedoms" for their invasion. From the German point of view, the Thirty Years' War was proof of their vulnerability to foreign aggression. Atrocities such as the "sacking" of Magdeburg in 1631, where more than 30,000 people were killed, were embedded in the German consciousness. All told, 8 million people died during the Thirty Years' War.