Jul 2 Incident at Xuanwu Gate: Prince Li Shimin ambushes and kills his rivals, the brothers Li Yuanji and Li Jiancheng, sons of Emperor Gaozu; he then forces the emperor to name him as successor to the throne
Jul 29 Avars under khagan Bajan begin siege of Constantinople (fails, preserving the eastern Roman empire)
Aug 7 Battle at Constantinople: Slavic/Persians/Avarenvloot defeated
Sep 4 Shimin becomes Emperor Taizong of Tang, Emperor of China, when his father abdicates in his favour
Gregory I
Gregory XIII
Julius II
Julius III
Leo X
Pius V