May 20: National Day of Remembrance in Cambodia (1975); National Awakening Day in Indonesia (1908) 325 – The First Council of Nicaea (depicted), the first ecumenical council of the Christian Church, was formally opened by Constantine the Great. 794 – According to the Anglo-Saxon Chronicle, King Æthelberht II of East Anglia was beheaded on the orders of Offa of Mercia. 1714 – J. S. Bach led the first performance of his Pentecost cantata Erschallet, ihr Lieder at the chapel of Schloss Weimar. 1927 – With the signing of the Treaty of Jeddah, the United Kingdom recognized the sovereignty of Ibn Saud over Hejaz and Nejd, which later merged to become Saudi Arabia. 1941 – World War II: German paratroopers began the Battle of Heraklion on the island of Crete, capturing the airfield and port in Heraklion ten days later. William Fargo (b. 1818)Gertrude Guillaume-Schack (d. 1903)Nizamuddin Asir Adrawi (d. 2021) More anniversaries: May 19 May 20 May 21 Archive By email List of days of the year About