Probably not super helpful/what you’re looking for, but one broad category of groups who go from ‘doing violence’ to ‘doing much less or no violence’ (often within a short space of time) are resistance organisations that successfully manage the transition, usually after achieving some level of progress. The ANC in South Africa seems like a good example. Sinn Féin in Ireland (established as the political wing of the IRA) is another.
Probably not super helpful/what you’re looking for, but one broad category of groups who go from ‘doing violence’ to ‘doing much less or no violence’ (often within a short space of time) are resistance organisations that successfully manage the transition, usually after achieving some level of progress. The ANC in South Africa seems like a good example. Sinn Féin in Ireland (established as the political wing of the IRA) is another.