Complex sentence: The introduction of the Imperial Order of St. Alexander Nevsky was planned by Russian Emperor Peter I of Russia and was established in Russia by Catherine I of Russia on May 21,1725 in memory of the deeds of Saint Alexander Nevsky in defending Russia against foreign invaders.
Split into simpler sentences: The introduction of the Imperial Order of St. Alexander Nevsky was planned by Emperor Peter I of Russia. It was established by Empress Catherine I of Russia on May 21,1725 in memory of the deeds of Saint Alexander Nevsky in defending Russia against foreign invaders.