The success of the Norman Conquest of Britain turned on one lucky break. For months, William of Normandy waited for an opportunity to cross the Channel and invade. But he needed favourable weather and the wind refused to co-operate. The Anglo Saxon King Harold, meanwhile, waited with his army and might well have defeated him. But only weeks before the wind changed, Harold received shattering news. The King of Norway had invaded Yorkshire with a huge Viking army and 300 ships. Harold had to race north at breakneck speed to defeat him and then, on hearing that William was finally crossing the Channel, race back down the length of England with his exhausted and depleted army to counter the Norman threat. Despite this, the Battle of Hastings was a "close run thing"; Harold's war-weary army very nearly won it. As we know, that didn't happen, and Harold's eventual defeat had the most dramatic effect of any defeat in the high Middle Ages. In a few short months, the ruler of northern France became the master of Britain and within a year or two had made his government effective across the whole country. It was a staggering military success, on a par with the First Crusade which followed it 30 years later. In this short, highly entertaining book, Daniel Gerrard tells the story of Britain before, during and after the Conquest, and explains how the Norman kings built on a highly effective Anglo Saxon framework to lay the foundations of modern Britain.