The 800s decade ran from January 1, 800, to December 31, 809.
The 820s decade ran from January 1, 820, to December 31, 829.
The 830s decade ran from January 1, 830, to December 31, 839.
The 840s decade ran from January 1, 840, to December 31, 849.
The 850s decade ran from January 1, 850, to December 31, 859.
The 860s decade ran from January 1, 860, to December 31, 869.
The 870s decade ran from January 1, 870, to December 31, 879.
The 780s decade ran from January 1, 780, to December 31, 789.
Year 840 (DCCCXL) was a leap year starting on Thursday in the Julian calendar, the 840th year of the Common Era (CE) and Anno Domini (AD) designations, the 840th year of the 1st millennium, the 40th year of the 9th century, and the 1st year of the 840s decade.
Year 855 (DCCCLV) was a common year starting on Tuesday of the Julian calendar.
Year 857 (DCCCLVII) was a common year starting on Friday of the Julian calendar.
Year 829 (DCCCXXIX) was a common year starting on Friday of the Julian calendar.
Year 852 (DCCCLII) was a leap year starting on Friday of the Julian calendar.
Year 853 (DCCCLIII) was a common year starting on Sunday of the Julian calendar.
Year 854 (DCCCLIV) was a common year starting on Monday of the Julian calendar.
Year 870 (DCCCLXX) was a common year starting on Sunday of the Julian calendar, the 870th year of the Common Era (CE) and Anno Domini (AD) designations, the 870th year of the 1st millennium, the 70th year of the 9th century, and the 1st year of the 870s decade.
Æthelwulf was King of Wessex from 839 to 858. In 825, his father, King Ecgberht, defeated King Beornwulf of Mercia, ending a long Mercian dominance over Anglo-Saxon England south of the Humber. Ecgberht sent Æthelwulf with an army to Kent, where he expelled the Mercian sub-king and was himself appointed sub-king. After 830, Ecgberht maintained good relations with Mercia, and this was continued by Æthelwulf when he became king in 839, the first son to succeed his father as West Saxon king since 641.
Æthelbald was King of Wessex from 855 or 858 to 860. He was the second of five sons of King Æthelwulf. In 850, Æthelbald's elder brother Æthelstan defeated the Vikings in the first recorded sea battle in English history, but he is not recorded afterwards and probably died in the early 850s. The next year Æthelwulf and Æthelbald inflicted another defeat on the Vikings at the Battle of Aclea. In 855, Æthelwulf went on pilgrimage to Rome and appointed Æthelbald King of Wessex, while Æthelberht, the next oldest son, became King of Kent, which had been conquered by Wessex thirty years earlier.
Year 893 (DCCCXCIII) was a common year starting on Monday of the Julian calendar.
Year 944 (CMXLIV) was a leap year starting on Monday of the Julian calendar.
