The Danes came to Ireland with nothing to do
But dream of the plundered old Irish they slew
"Yeh will in your Vikings", said Brian Boru
And threw them back in the ocean
The sea, oh the sea is the gradh geal mo croide
Long may it flow between England and me
It's a sure guarantee that some how we'll be free
Oh! thank God we're surrounded by water
The Anglo-Saxon Chronicles say Viking raiders struck England in 793 and raided Lindisfarne. That's LATE EIGHTH CENTURY ~ again, in the early 8th century they didn't have Viking Boats ~ which is the point. Without those boats they couldn't get away from the Baltic and were pretty much stuck with control over only a small bit of even the Norwegian West Coast.