Delegates gathered at Jefferson City on the 28th of February 1861 to begin their work. The assembly moved its meeting location to St. Louis Mercantile Library on the 4th of March.
Sterling Price served as chairman despite his conditional unionist stance. Robert Wilson became chairman of the remaining group after twenty delegates fled with Governor Claiborne Fox Jackson and Sterling Price.
The remaining convention members declared all state elective offices vacant on that summer day. Hamilton Rowan Gamble received appointment as governor while Willard P. Hall took the position of lieutenant governor alongside Mordecai Oliver as secretary of state.
Final deliberations occurred in June 1863 with the goal of eliminating slavery entirely but an ordinance passed establishing gradual emancipation completed on the 4th of July 1870. Thomas Clement Fletcher led a new convention elected in November 1864 which abolished slavery without compensation by a 60 to 4 vote on the 11th of January 1865.
All state officials faced mandatory loyalty oath requirements before holding office to ensure strong Union support in future elections. These measures ensured political dominance for unionist factions throughout the war years and successfully suppressed Confederate sympathizers from influencing local governance.