In fiction (and in Real Life) during a great war there's a certain strategic loss that is very significant to the point of being demoralizing, shocking, and Iconic in universe. One faction might be fighting an intergalactic war with Scary Dogmatic Aliens, But there's one place in the galaxy that has no chance in hell of falling at the hands of the enemy. Perhaps it's a planet that's fortified by [...] [tvtropes.org]