I am not sure if it counts as English, but the poem "The Battle of Maldon" is very old. I copy below something from a website: www.airflow.net/maldon/ which I found from a quick search on google:-
In 1995 AirFlow Design placed a short page on the World Wide Web describing the last stand of Byrhtnoth, Earl of Essex, against a Viking horde in the year of our Lord, 991. A thousand years ago, an anonymous Anglo Saxon writer immortalised the event with the now famous poem, and in the past 2 years our site has become a major World Wide Web resource for the Battle of Maldon, 991AD.