After a demonstration against the Galactic Empire was staged by the inhabitants of the Sulon moon, the Empire's response was brutal: they slaughtered three families who had participated in the protest.
Prior to 1 BBY, several Sulonese farmers and colonists voiced their discontent with Imperial policies, ultimately culminating in a public, peaceful demonstration in the city of Barons Hed. Imperial forces moved to suppress the gathering, but the demonstrators dispersed before they arrived.
To avoid looking weak, the local commandant decided to use recorded holovids (aided by a traitor's assistance) to identify and pursue the demonstrators.
Imperial Intelligence reports indicated to All Terrain Armored Transport crews that the colony harbored approximately four hundred Rebels. The walker operators then aimed to eliminate as many individuals as possible. One walker intentionally targeted a dormitory, and when twenty to thirty civilians emerged from the debris to surrender, they were deliberately targeted and killed by the walker's cannons.
The assault resulted in the death of three families, including Katie Grawley.
There is some inconsistency in the timeline of the massacre between the Dark Forces: Rebel Agent novel and the audio drama. The novel implies that following the massacre, the Rebels agreed to heed Morgan Katarn's advice and departed for Ruusan.
Conversely, the audio drama suggests that Morgan, anticipating a dire outcome, convinced the demonstrators to evacuate the planet as a precaution. Most of the Rebels were already far from Sulon when the Empire launched its attack, except for three families who chose to remain and lost their lives. On the same day as the event, Morgan revealed their secret destination to the Rebels, and after some initial skepticism and complaints, he informed them of the morning's events, and the fate of their friends who had not heeded his warning.