Original: After Napoleon's defeat in 1814 and the Prussian occupation of Paris by General Ernst von Pfuel, the Quadriga was restored to Berlin and Victoria's wreath of oak leaves was supplemented with a new symbol of Prussian power, the Iron Cross.
Simplified: When Napoleon was beaten in 1814 Prussian General Ernst von Pfuel occupied Pais and took the Quadriga back to Berlin, the olive wreath was changed to an Iron Cross.