The Clontarf Split

It was 1014 when the Battle of Clontarf was fought, with Brian Boru's forces against Máel Mórda mac Murchada 's forces. Alongside him were Viking mercenaries from as far as the Orkney Isles, united under Sigtrygg Silkbeard.

After hours of battling, Murchada's forces were finally plunged through and routed. At the last possible moment, before Brian's forces could reach the fortress of Dublin over the bridge, Malachy II re-entered the battle.

POD vs. OTL
Brian Boru has already been slain by Brodir after the successful rout of Murchada's forces, leaving his men to fair under his remaining sons and generals.

In OTL, Malachy's forces meet Brian's at the bridge and are, just as their allies under Murchada had done before, routed to the sea this time, where Brian's forces successfully capture Dublin.

However, our POD begins with the victory of Malachy's forces. Instead, Brian's men are routed away into the sea or are killed before reaching the fortress.