elephantocetomachia
n. a fight between an elephant and a whale

Anthony R. Wagner uses this word in his foreword to G.D. Squibb’s 1959 book The High Court of Chivalry to describe the controversy in early 20th-century England over the right to bear arms:

I therefore soon found myself studying the whole subject with close attention and in time I came to two conclusions. The first was that the original controversy had been an elephantocetomachia, a fight between an elephant and a whale, incapable of decision because the adversaries lived in different elements and could not come to grips. Oswald Barron, a historian, was trying to settle a legal question by reciting history. [A.C.] Fox-Davies, a lawyer, hoped to settle history by quoting law.

Wagner doesn’t claim to have coined it, but I can’t find it anywhere else except in quotations of that passage. That’s a shame — it’s a useful word.

(Thanks, Julian.)