Under Harald Bluetooth, Denmark became a powerful unified kingdom. But not powerful enough to take on the Germans. Harald strengthened the southern border defenses and erected the trelleborg fortresses all over his realm. This shows not only that the Danes had impressive engineering know-how and considerable political, financial and military resources--but also that Harald was scared enough of the Germans to pay for it all. In the end, though, his downfall would come from much closer to home.