A book where a pacifist or similar moral construct has to chose to uphold their ideals or allow world changing event to happen that are within their control. Sci-fi setting preferred

Maybe this doesn’t even exist as a plot of a book. But I’d like to see someone’s pacifism put to the real test. And I would definitely prefer to see this in a sci-fi setting. I’m not a big fantasy guy. So even in a hypothetical, modern world with different political factions, fighting for overall world power is fine.

by highcaliberwit