Complex sentence: During the Napoleonic invasion of Russia in 1812 Russian Imperial cavalry, artillery and cossacks regiments ambushed and routed the Duchy of Warsaw 3 uhlan divisions (Battle of Mir (1812)), and then Russian, withdrawing east, abandoned the town and dynamited the castle.
Split into simpler sentences: During the Napoleonic invasion of Russia in 1812, Russian Imperial cavalry, artillery and cossack regiments ambushed and routed the Duchy of Warsaw 3 uhlan divisions (Battle of Mir (1812)). The retreating Russians, withdrawing east, abandoned the town and dynamited the castle.