Who established the military decoration of the Iron Cross?

The Iron Cross (German: About this soundEisernes Kreuz (help·info), abbreviated EK) is a former military decoration in the Kingdom of Prussia, and later in the German Empire (1871–1918) and Nazi Germany (1933–1945). It was established by King Frederick William III of Prussia in March 1813 backdated to the birthday of his late wife Queen Louise on 10 March 1813 during the Napoleonic Wars . Louise was the first person to receive this decoration (posthumously).