To win the war and lose the peace is folly.
4 seconds sound clip from the Alexander the Great (1956) movie soundboard.
You can hear this line at 00:48:06 in the Blu-ray version of the movie.
Quote context
[...]
- And there, in Athens, a treaty of peace will be drawn up between us by my son Alexander.
- To all those who died like men on the bloody field of Chaeronea, all hail!
- Alexander rides to Athens, and I stay here.
- To win the war and lose the peace is folly.
- When and where will I meet that dagger, friend?
- To my humble home, Alexander, and in the name of Athens, I bid you welcome.
- Oratory, Demosthenes, is a noble profession, and, I am told, a rewarding one.
- How humble is your home, Aeschenes?
[...]