23 events the sources record for this year, grouped by region.
What happened
China (20)
Li Guangbi and Guo Ziyi advanced to Jingxing, crushed Shi Siming, and recovered more than ten prefectures and counties. (Old Book of Tang (Jiu Tangshu), Annals 舊唐書 卷9 天寶15年 2月)
Geshu Han fought Cui Qianyou at the Lingbao Xiyuan with 80,000 men and was crushed; six or seven out of ten of his men died. (Old Book of Tang (Jiu Tangshu), Annals 舊唐書 卷9 天寶15年 6月)
Geshu Han was captured by his subordinate Huoba Guiren and surrendered to the enemy, and Tongguan could not be held. (Old Book of Tang (Jiu Tangshu), Annals 舊唐書 卷9 天寶15年 6月)
Crown Prince Li Heng ascended the throne at Lingwu; the ministers, citing that the retired emperor had transferred the throne, prayed for his long life. (Old Book of Tang (Jiu Tangshu), Annals 舊唐書 卷10 至德1年)
Geshu Han suffered a crushing defeat at the hands of An Lushan's army at Xiyuan in Lingbao. (New Book of Tang (Xin Tangshu), Annals 新唐書 卷005 睿宗·玄宗 天寶15年6月)
While Emperor Xuanzong was fleeing to Shu, Chen Xuanli killed Yang Guozhong at Mawei and ordered Consort Yang to die (the Mawei post incident). (New Book of Tang (Xin Tangshu), Annals 新唐書 卷005 睿宗·玄宗 天寶15年6月)
When Aistulf breaks his promise, Pippin again enters Italy, besieges him in Pavia where he is shut up, and forces him to comply; he hands Ravenna, Pentapolis and the exarchate over to Saint Peter (Royal Frankish Annals ARF(Einhard판) a.756, Kurze 1895 p.15)