In September, 1792, King George III dispatches the first British trade mission to China. Under the leadership of Lord George Macartney, the delegation intends to persuade Emperor Qian-long to open his country for trade with the West. After months of Qian-long's stalling tactics, the Brits take a three day journey out from Beijing, to be greeted with a view few Europeans had seen before: the Great Wall winding its way across mountains, valleys and verdant plains. Macartney believed this was "the most stupendous work of human hands," and this perception of the "Great Wall" would endure to this day. But China was surrounded by not one, but two walls: a physical and a mental one. Since the Ming Dynasty (AD 1368-1644), China had tried to shut itself off from the outside world. Mongol and later Manchu invaders found gaps in the northern frontiers. One of the most tenacious opponents, Altan Khan (16th century), even dared lay siege to Beijing. As a result, the walls were fortified even further, fortresses and garrisons were built. Finally, the wall reached the sea, enclosing China and shutting out anything foreign for centuries to come. Eventually, this attitude was the Ming Dynasty's undoing. In 1644, a rebel Manchu took the Dragon Throne. Macartney's mission (in the late 18th century) was a colossal failure, but his assessment of the Great Wall remained deeply engrained in the minds of Westerners, a myth that shrouds the true story of the wall even today.