Part 2 examines how the freewheeling modernism that had shocked audiences in the first two decades of the century came under state control. Initially, many practitioners thought the totalitarian regimes would be good for music and the arts. What followed in Germany was a ban on music written by Jews, African-Americans and communists, while in the Soviet Union there was a prohibition on music the workers were unable to hum. After the cataclysm of the 1940s, a new generation of composers - Boulez, Stockhausen, Xenakis, Nono, Ligeti - turned their back on what they saw as the discredited music of the past and tried to reinvent it from scratch. Or, at least, from serialism, which became as much of a straitjacket as totalitarianism's strictures had been. But from this period of avant-garde experimentation, which many listeners found baffling and terrifying, came some of the most influential and radical musical innovations of the century.

Andrew Graham-Dixon continues his exploration of German art by looking at the tumultuous 19th and early 20th centuries, and how artists were at the forefront of Germany's drive to become a single nation. Andrew travels to the north and the coastal town of Griefswald, the birthplace of Caspar David Friedrich, the most influential of the German Romantics, to discover how the Baltic coast impacted his mysterious paintings of the German landscape. He also visits Berlin and explores the art of the powerful Prussian state, which would spearhead the unification of Germany in 1871. The episode ends with the outbreak of World War I and the attempts of the artists Franz Marc and Otto Dix to rationalise the catastrophic experiences of the world's first technological war, a war driven by the Prussian innovations.

The German army launched Operation Barbarossa, the invasion of the East, with supreme confidence in its own superiority. High Command was sure that victory would come as quickly and as easily as in France. At the onset, the troops advanced rapidly and the Panzer forces under General Guderian were unbeatable. There were, however, far more casualties and more wear-and-tear on equipment than anticipated. The invading force got bogged down short of Moscow and the withdrawal from there was a severe psychological blow to the men. When an extremely severe winter set in, morale sank further. The soldiers were not equipped for such low temperatures and their guns and machinery could not cope. Hitler ordered his troops to stand firm.

Among the ranks of the Wehrmacht there was limited opposition to Hitler. Most officers initially felt enthusiastic about the prospect of war and were grateful to Hitler whose war-mongering had furthered their personal careers. Furthermore all soldiers had to make an oath of allegiance to the Führer and, up until the very end, there were many who felt unable to break this pledge. There were, however, some officers who opposed Hitler. For some it was on moral grounds and for others because they thought that his military tactics would lose them the war. There were plots against Hitler and attempted coups, the best known being the July bomb plot led by Claus von Stauffenberg. Some soldiers refused to bear arms and were shot, others deserted, others still carried out quiet acts of sabotage and subversion. By and large, however, the Wehrmacht carried out the orders Hitler issued, even if it involved perpetrating acts of atrocity.

The determination of the German forces to keep on fighting in the face of defeat had disastrous consequences. After the Allied landings in the summer of 1944, the Wehrmacht was on the defensive on all fronts. It was clear to the German generals interned at Trent Park that Germany would soon lose the war. In mid-1944, Gerhard Graf von Schwerin chose to use common sense instead of blindly obeying Hitler's orders. He decided to surrender the city of Aachen to the US army to avoid bloodshed. Other commanders such as Field Marshal Ferdinand Schorner kept on pushing their soldiers to give their all. Despite being outnumbered by the Soviet forces, Schorner forced his soldiers to hold out in Sworbe, a 200 square kilometre peninsula on the coast of Estonia. Thousands of soldiers died. Yet Schorner's attitude and the urging by Hitler and Goebbels to hold out were accepted by a large number of young soldiers. By April 1944, the Ruhr pocket was completely surrounded, yet Field Marshal Model refused to surrender, so that 1.2 million German soldiers and a large number of Allied soldiers died between January and May 1945.

There is a tendency to deny German culture the equal reverence of Italy or Spain, and this enlightening new series provides a wonderful opportunity to explore a great, yet often neglected, artistic tradition whose influence has been just as profound. Andrew Graham-Dixon concludes his exploration of German art by investigating the dark and difficult times of the 20th century. Dominating the landscape is the figure of Adolf Hitler, failed artist, would-be architect and obsessed with the aesthetics of his 1,000-year Reich". In a series of extraordinary building projects and exhibitions, Hitler waged a propaganda war against every form of modern art as a prelude to unleashing total war on the whole of Europe. After the war the shadow of the Third Reich persisted, Germany remained divided and traumatised. How would artists deal with a past that everybody wanted to forget? Journeying through the work of Otto Dix and George Grosz and the age of the Bauhaus to the post-war painters Georg Baselitz, Hilla Becher and the conceptual artist Joseph Beuys is a long and strange journey, but the signs that art has a place at the heart of the new reunited Germany are clearly visible.