Naval warfare had incredibly negative effects on civilians in wwi with blockades and unrestricted submarine warfare; explain how these tactics could be justified by the nations using them.

It was one of the biggest factors that could affect whether the countries would win or lose the war. It was all about balancing of interests or cost-benefit analysis. Yes, it had negative effects on civilians. But this effect could be justified by the greater good. It was more important to do everything they could to win the war rather than not engage in naval warfare for the sake of the civilians which would result in certain loss in the war which would, in turn, create an effect on the civilians which is worse than the effect of the naval warfare itself.