Complex sentence: The remainder of northern and western France was placed under German military control, while unoccupied southern metropolitan France and the French empire were placed under the control of Vichy, a new collaborationist French government.
Split into simpler sentences: The remainder of northern and western France was placed under German military control. Unoccupied southern metropolitan France and the French empire were placed under the control of the Vichy Regime, a new collaborationist French government.