Hannibal got away from a Roman force sent to fight him in Gaul. He then went up the valley of one of the streams of the Rhône River. By Autumn, he reached the foot of the Alps. His journey over the mountains is one of the most famous achievements of any military force. After this journey, Hannibal came down from the foothills into northern Italy, to the surprise of the Romans. He had arrived with only half the forces he had started with and only a few elephants. Hannibal had lost as many as 20,000 men crossing over the mountains.