Arpeggio of Blue Steel (Aoki Hagane no Arpeggio) is a fairly recent manga by Ark Performance, centering on humanity, having been pushed back from global warming raising the sea level, and their conflict with the Fleet of Fog, archaic-looking WWII-era ships who have been using Game Breaker weapons and armor to ensure that humans can't set keel or pontoon into the world's oceans without risking getting blown to smithereens. The world's navies banded together 17 years before the opening chapters of the manga and were utterly annihilated.