Henry is furious and desires to avenge the Polish intervention that had caused his Hungarian fiasco.

He is poised to invade Poland in the summer of 1109 when the Polish ruler organizes an expedition into Pomerania in order to secure his northern boundary.

According to Gallus Anonymus, the purpose of the expedition wasn't just the taking of the castle of Nakło, but to force the Pomeranians into a decisive battle.

Gallus describes the battle in the first chapter of the third book of his chronicle.

On August 10, 1109, Boleslaw's force, which is besieging Naklo, engages the Pomeranian relief forces and defeats them.

As a result, the city surrenders to him.

Later, Boleslaw will incorporate Pomerania into his realm.

In Gallus' chronicle, the defeat of the Pomeranians and their conversion to Christianity are presented as one of Boleslaw's great achievements, comparable to the victory of King Otto I of Germany over the Hungarians at the 955 Battle of Lechfeld.

Boleslaw shortly afterwards has to rush to the south to meet Henry and his Imperial army at the Battle of Glogów.

He will later send Bishop Otto of Bamberg as a missionary to christianize Pomerania.