Although his crossing of the Alps with the elephants is widely remembered, Hannibal made surprisingly little use of them. War elephants proved useful against Iberian tribal forces, though they were somewhat less effective when facing disciplined regulars (see The Trouble with Elephants). In fact, most of the 34 elephants he started with died during the mountain passage or during the severe winter that followed. The last few died after the battle of Trebbia, leaving only one (Serus?) to carry Hannibal through the Etrurian marshes.