5 events the sources record for this year, grouped by region.
What happened
Japan (4)
On the sixteenth day of the fifth month, Dewa reports that on the mountain of the Ōmonoki shrine in Akumi district a fire broke out on the eighth day of the fourth month, burning soil and stone with a thundering sound; the river turned into blackish muddy water, fish died in droves and rice fields were washed away (the eruption of Mount Chōkai). (Nihon Sandai Jitsuroku 卷第十九 貞觀13年5月十六日 (원문 19.96))
On the seventh day of the intercalary eighth month, thunder and heavy rain suddenly cause the river to overflow; the roads and bridges of the capital are swept away and houses collapse. An envoy is sent to make offerings at the shrines to pray for the rain to stop. (Nihon Sandai Jitsuroku 卷第二十 貞觀13年閏8月七日 (원문 20.58))
On the twenty-eighth day of the ninth month, Empress Dowager Fujiwara no Junshi, mother of Emperor Montoku, dies. (Nihon Sandai Jitsuroku 卷第二十 貞觀13年9月廿八日 (원문 20.80))
On the fourteenth day of the twelfth month, the Onyōryō says an epidemic will come next year, and the old folk say a year when flowers bloom in winter brings a great plague across the realm; offerings and sutra recitations are ordered in the provinces of the Five Capitals and Seven Circuits. (Nihon Sandai Jitsuroku 卷第二十 貞觀13年12月十四日 (원문 20.137))
Western Europe (1)
When the army came to Reading in Wessex, Æthelred and Alfred met them with a great host and fought; great slaughter on both sides. (Anglo-Saxon Chronicle Giles/Ingram 1847 A.D. 871 항 (pg657.txt 줄 2763))