The Insiders were an unsanctioned military organization within the Combined Defense Forces of the New Republic. Their purpose was to halt the advance of the Yuuzhan Vong both during their invasion of the galaxy and following the decline of the New Republic.
After the Yuuzhan Vong captured Coruscant, elements of the New Republic military, led by Wedge Antilles, withdrew to the planet Borleias to reorganize alongside other loyalists, including members of the Jedi Order. During a high-level meeting on Borleias, the group abandoned their original objective of locating key Republic military figures Garm Bel Iblis and Traest Kre'fey because the sudden arrival of the remaining members of the Republic's Advisory Council took precedence.
Antilles was compelled to negotiate with the Council and agreed to defend the planet against overwhelming enemy forces if Senator Pwoe, who had proclaimed himself Chief of State, would accept his terms. Considering the Advisory Council ineffective and obsolete after the agreement was reached, Antilles sought counsel from Jedi Master Luke Skywalker of the Jedi Order. Skywalker suggested subtly undermining the Council to improve its effectiveness, recalling the combat tactics of the Rebel Alliance, and these discussions led to the formation of the Insiders. Subsequently, Han Solo and Leia Organa Solo, along with other members, established resistance networks on various planets without informing the Republic of their operations.