After organization, the new regiment was assigned to the First Missouri Brigade. The First Missouri Brigade, commanded by Colonel Francis M. Cockrell, was transferred to the vicinity of Grand Gulf, Mississippi in early March 1863. While at Grand Gulf, the brigade built fortifications. The 1st and 4th Missouri (Consolidated), along with the 2nd Missouri Infantry, 3rd Missouri Infantry, and Henry Guibor's artillery battery, crossed the Mississippi River to Louisiana to observe Union movements. On April 15, the Missourians were ordered back to Grand Gulf, and the regiment participated in artillery fire with Union naval ships at the Battle of Grand Gulf. After Union Major General Ulysses S. Grant landed in Mississippi in order to move against Vicksburg, Bowen sent many of his men from Grand Gulf to Port Gibson, Mississippi to try to stop Grant. However, the 1st and 4th Missouri (Consolidated) was on detached duty guarding a bridge, and missed the ensuing Battle of Port Gibson on May 1.