Dresden was the capital city of the Saxony region of the nation-state Germany on Earth.
In 1945, Dresden was firebombed by the Allies during World War II, killing tens of thousands of people. Unbeknownst to the general population at the time, Starfleet officers Anne Lansing, Daniel Radke and Antonio Fernandes successfully stopped an alien invasion, using the bombing to destroy the aliens and restore the timeline. (Star Trek: The Cantabrian Expeditions: "Hemorrhage")