Shame on you. This is what really happened. Always trust the author. The answer is of course Algis Budrys. I got a mental crash of gears on reading this and had to look it up.
Nobody likes a smartass.
Because SF fans don't read A.E. Housman's verse. Speaking of Against the Fall of Night , here's a poser for you. The new edition contains quite a nifty sequel to the original story, by Greg Benford. But one of the unforgettable reversals in both Clarke's original and its expansion The City and the Stars is the discovery that the ancient fortress of Shalmirane wasn't built for war. It had been used to destroy the Moon, whose decaying orbit threatened Earth.