A quotation from the full collection:

If you will not fight for the right when you can easily win without bloodshed, if you will not fight when your victory will be sure and not too costly, you may come to the moment when you will have to fight with all the odds against you and only a small chance of survival. There may even be a worse case: you may have to fight when there is no hope of victory, because it is better to perish than to live as slaves.

—Winston Churchill