In Rivers of Africa (1893), Winston Churchill observed:

If you will not fight for right when you can easily win without bloodshed; if you will not fight when your victory is sure and not too costly; you may come to the moment when you will have to fight with all the odds against you with only a precarious chance of survival. There may be a worse case. You may have to fight when there is not hope of victory at all, because it is better to perish than to live as slaves.

(Thanks to JP)