Water levels on the Danube River, the second longest in Europe, have dropped so low because of drought that the hulks of dozens of Second World War German battleships are emerging into view. The Danube’s record low water levels have also forced power plants to the brink of shutting down, and governments across Central and Eastern Europe are taking steps to conserve electricity.Advertisement In the middle of the river separating Serbia and Romania near the Serbian port of Prahovo, a rusty hull is now visible along with a broken mast where the Nazi flag used to fly. The wreckage of...