I don't know about war.
4 seconds sound clip from the It's a Wonderful Life (1946) movie soundboard.
You can hear this line at 00:40:27 in the Blu-ray version of the movie.
Quote context
[...]
- Well, how do you know? What, did she discuss it with you? No. Well, then how do you know?
- Well, I've got eyes, haven't I?
- Why, she lights up like a firefly whenever you're around.
- Besides, Sam Wainwright's away in New York, and you're here in Bedford Falls.
- And all's fair in love and war.
- Well, here's your hat. What's your hurry?
- All right, Mother, old Building and Loan pal,
- I think I'll go out and find a girl and do a little passionate necking.
[...]