A key event during the First Jedi Purge, the blockade of the planet Onderon marked the initial conflict of the Onderon Civil War. General Vaklu, who was the leader of Onderon's armed forces and the cousin of Talia, the ruling queen of Onderon, disagreed with Talia's policies, which he considered too accommodating towards the Galactic Republic. Vaklu secretly allied himself with the Sith, and when they informed him that Meetra Surik, known as the Jedi Exile, was soon to arrive on Onderon, he saw an opportunity to seize power from his cousin and tarnish the Republic's reputation among Onderon's citizens. Colonel Tobin, Vaklu's trusted second-in-command, was placed in charge of the planet's orbital defenses while Vaklu went to Iziz, Onderon's capital city. Tobin then implemented a blockade around Onderon, ordering the seizure and inspection of all Republic vessels. This caused delays and frustration for pilots seeking to land and deliver their cargo. The situation worsened with the arrival of the Ebon Hawk. Claiming that the Exile had initiated the attack, Tobin commanded the Onderon military to open fire not only on the Ebon Hawk, but also on other freighters in orbit awaiting docking clearance.
Vaklu declared martial law, thereby taking control of Iziz. He falsely claimed that Tobin was a hero who had been attacked without provocation, and that fifteen (instead of the actual six) of their defense ships had been destroyed. He also spread misinformation, telling the public that the Hawk was a large warship. The Exile escaped to Dxun, Onderon's moon. Although most of the Onderon military remained loyal to Talia, they were unable to withstand the Sith armada that swiftly arrived to support Vaklu's bid for the throne.