The decades-long war between the Galactic Republic and the rejuvenated Sith Empire ended without a decisive battle. Instead, the conflict halted with a peace agreement neither side believed would last--the Treaty of Coruscant, a document forbidding Republic military activity within Imperial space and vice versa. Rules of engagement in neutral territory are far more vague, allowing for a range of border conflicts and attacks via third parties, but the treaty has prevented all-out warfare on more than one occasion.
Negotiations began when the Empire--whose early victories had led to dwindling resources and overexpansion--reached out to a battered Republic and called for a summit on Alderaan. As the summit began, Imperial forces launched a surprise attack on Coruscant, the Republic capital. Conquering the city-world was impossible, but the Empire wreaked enormous havoc in a short period, effectively holding Coruscant hostage and forcing the Republic to agree to less-than-favorable terms.