Prelude to the Warsaw Uprising
The Warsaw Uprising occurred at a stage of the Second World War when it was becoming clear that Nazi Germany was likely to lose. The Uprising ended in capitulation, the deaths of between 150,000 and 200,000 Polish civilians, and only 15% of Warsaw intact; with the benefit of hindsight, many people have argued that it should never have been started.
Source: Wikipedia — Prelude to the Warsaw Uprising (CC BY-SA 4.0)