World War II: <a href="https://en.wikipedia.org/wiki/Bombing_of_Hamburg_in_World_War_II" id="mwuQ" rel="mw:WikiLink" title="Bombing of Hamburg in World War II">Operation Gomorrah</a>: The Royal Air Force bombs <a href="https://en.wikipedia.org/wiki/Hamburg" id="mwug" rel="mw:WikiLink" title="Hamburg">Hamburg, Germany</a> causing a <a href="https://en.wikipedia.org/wiki/Firestorm" id="mwuw" rel="mw:WikiLink" title="Firestorm">firestorm</a> that kills 42,000 German civilians.