Explanation: From wiki:
The Anglo-Saxon Chronicle and the Chronicle of Henry of Huntingdon has it that one of the Norwegians (possibly armed with a Dane Axe) blocked the narrow crossing and single-handedly held up the entire English army. The story is that this Viking alone cut down up to 40 Englishmen and was defeated only when an English soldier floated under the bridge and thrust his spear through the planks in the bridge, mortally wounding the warrior.[18][19] His name was not preserved in the aftermath of this battle.
This delay had allowed the bulk of the Norse army to form a shieldwall to face the English attack.