With the partitioning of Ireland the Parliament of Northern Ireland built a new state designed to ensure ongoing control by Unionists. They marginalized the nationalist community, the progressive labor movement and those unionists not committed to the realization of a sectarian state.
They ensured their control through gerrymandering of constituencies; the use of Special Powers and the formation of a sectarian police force; and the use of social and economic policies designed in the interest of the majority population.
Reforms after World War 2 in education and in the provision of welfare benefits played a part in radicalizing the generations in the 1950's and 1960's who sought to change the reality for their communities. The Civil Right Movement sought to reform the Unionist state but their efforts were met with violent resistance on the basis that changes would undermine the nature of the Unionist state. Reform was not an option.
The Civil Rights campaign was criminalized and attacked to the point that nationalist areas had to rely on self defense against drive-by shootings, bombings and pogroms by loyalists, police raids, and after 1969 from British army activity. By the late 1960's the IRA had been weakened and had little capability to effectively defend nationalist areas. The violence against the nationalist population led to the formation of the Provisional IRA and to another devastating war in the centuries old imposition on the people of Ireland by a foreign government.