Hannibal Crosses The CarpathiansWhen did Hannibal cross the alps? According to http://carpenoctem.tv/military/hannibal.html it was in 218 B.C. Why did Hannibal take elephants to cross the alps? Hannibal took elephants across the Alps as weapons of war against the Romans. How many men crossed the alps with Hannibal? 50,000 infantry, 9,000 cavalry, and about 30 elephants when he first began the ascent. How many elephants did Hannibal have before he crossed the alps? Fifty