Ord Mantell massacre

In the aftermath of her defection from the Alliance during the Battle of Odessen in 3630 BBY, the former Knight of Zakuul Senya Tirall traveled to the planet Ord Mantell to meet with a group of Knights who opposed her daughter Vaylin's rule—only to find that Vaylin had arrived before her and massacred the entire group. Vaylin used the slaughter as a trap for her mother, engaging her in a duel that only ended when her weapon pierced the hyperdrive of a nearby damaged starship and caused a massive explosion. To Tirall's surprise, Vaylin shielded both of them with the Force, and she was able to escape from her daughter and flee the planet with her critically-injured son, Arcann.

Text and facts from the “Ord Mantell massacre” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.