Historical Linguistics and Language Families 8, Exercise 2: English events

Anglo-Saxon settlement   c. 450 (settlers arrived in the mid-5th to 7th
                         centuries). Consequence: their Ingvaeonic dialects
                         displaced Celtic languages and possibly British
                         Latin in much of England.
Great Heathen Army       865. Consequence: much of northern and eastern
                         England came under Scandinavian control (the
                         Danelaw); English borrowed about 2,000 Old Norse
                         words, and Norse contact is believed to have
                         contributed to grammatical simplification.
Norman Conquest          1066. Consequence: Anglo-Norman replaced English for
                         a time as the language of the upper classes; about
                         10,000 French and Norman loanwords entered Middle
                         English.

Source: Wikipedia, History of English. The page notes the 449 account in the
Anglo-Saxon Chronicle was not a contemporaneous source.