Where was the first time since the civil war that a states armed forces were used to oppose the authority of the federal government?

The first instance since the Civil War where a state's armed forces were used to oppose the authority of the federal government occurred during the Alabama National Guard's involvement in the desegregation crisis at the University of Alabama in 1963. Governor George Wallace famously stood in the schoolhouse door to block the enrollment of African American students, defying federal orders. This confrontation highlighted the state's resistance to federal desegregation efforts and brought national attention to the Civil Rights Movement.