Tactical discussion: Countering Mumakil

[Lindolirian]

Other than shouting, "Ware! Ware!" and appealing to the Valar for help, you mean? According to the History Channel, Hannibal's elephants took fright at the Romans' horses and were much less aggressive in their presence. EDIT: After further research I found that it was actually the other way around, but horses could be trained to withstand elephants in which case the elephants were repelled by the smell of horses. And Wikipedia.com tells me this:

A reportedly effective anti-elephant weapon was the pig. Pliny the Elder reported that "elephants are scared by the smallest squeal of a pig" (VIII, 1.27). A siege of Megara was reportedly broken when the Megarians poured oil on a herd of pigs, set them alight, and drove them towards the enemy's massed war elephants. The elephants bolted in terror from the flaming squealing pigs.

But who knows how much spare bacon the Gondorians had to fry up just for their breakfast guests from Harad?