The obvious counter example is WWII. The victorious Allied forces conducted widespread strategic bombing campaigns and starvation blockades against Axis civilia

The obvious counter example is WWII. The victorious Allied forces conducted widespread strategic bombing campaigns and starvation blockades against Axis civilian targets. This was highly effective and saved the lives of many Allied personnel but judged against some modern criteria could have been considered "war crimes": for example, see the fire bombing of Dresden. None of the Allied leaders were put in front of a tribunal because the strategy worked and Congress was fully on board. The uncomfortable reality is that sometimes the only practical way to win and preserve your own forces is to massacre enemy civilians on an industrial scale.