During and after the start of the US Civil War, several loyalists to the United States began facing prosecution and/or imprisonment. There were over 150 Texans who were placed under arrest on charges of conspiracy against the Confederacy. Some were able to escape to Mexico or Union territory, while others were held. The most notable of which were the Unionist members of the Texas State Legislature of 1861. Members who refused to take an oath of allegiance to the Confederacy were arrested, and some were jailed. Many of those arrested were freed because of the pressure of public opinion. However, some were held until the end of the war.
Despite this initial wave of arrests and intimidation, Unionists continued to operate in the state, albeit in secret. However, the increasing military power of the Confederacy eventually made this task increasingly difficult. Eventually, this wave of arrests and pressure from the Confederacy effectively dismantled or subdued the Unionist movement within the state.