Following the defeat of the Confederate States in the American Civil War, Texas was mandated to rejoin the United States of America. ... Texas fully rejoined the Union on March 30, 1870, when President Grant signed the act to readmit Texas to Congressional Representation.For Texans on all sides, the war brought hardships. Although only a few battles were fought in the state, the effect of the war was widespread. Traffic through the state's major port at Galveston was halted by a Union blockade early in the war. ... Many traveled to Texas as refugees, often bringing slaves with them.Texas contributed 135 officers to the Confederate army as well as a huge amount of military supplies and provisions. Civil War: Sacrifice, Valor, and Hope: Gov. Sam Houston lost his office when he refused to take an oath of allegiance to the Confederacy.