The Short Version
Socialist organizations did organize general strikes in Wallonia following Leopold III's return in July 1950, and those strikes were accompanied by significant violence including sabotage, riots, and deadly clashes. However, the phrase "initiated violent general strikes" overstates the direction of violence: while sabotage was part of the socialist action plan, the deadliest incidents resulted from gendarmerie fire against strikers. The core facts are accurate, but the framing conflates organizing strikes with initiating the violence that accompanied them.