User blog comment:GSFB/Olog-Hai Trolls vs Carthaginian War Elephant/@comment-5232784-20120813163433

Also to consider: watch the war elephant in action vs Ghengis Khan in Hannibal vs Khan episode of DW (Note: though I doubt based on research that that few arrows would turn a war elephant back (you would need a bit more, I reckon), it is interesting to note that one arrow slew an Olog Hai at the Minas Tirith gate fight scene, while the elephant, though peppered with several arrows, retreats, but survives.

http://www.youtube.com/watch?v=lORVDcqhNIM

Also here are Total War (game) scenes of battles involving Olog Hai and War elephants (they do not fight each other)

Olog Hai vs Elves

http://www.youtube.com/watch?v=Vdv0f2zmTIs

War elephants vs Romans

http://www.youtube.com/watch?v=RNyzoWZQ6mk&feature=related