Just after dawn on May 26, while the Polish troops were still marching toward the bridges over the Narew River, Russian forces under the command of Dybich started their rapid advance towards Ostrołęka. Despite Polish resistance, the town fell into Russian hands, and to make things worse, they captured a bridgehead on the western bank of the river. Dybich did not hesitate – he immediately ordered his artillery to take up positions along the higher, eastern bank of the river and began shelling the approaching Polish units.The Polish commander, general Skrzynecki, was determined to destroy the Russian bridgehead at all costs. However, all the units that advanced towards it suffered heavy losses from artillery fire. Meanwhile, the Russians ferried additional brigades across to the western bank and expanded the area they controlled. Soon afterward, the Russians went on the offensive, halting their own artillery fire. The Poles seized this opportunity and launched one more attack that managed to stop the enemy advance, forcing Russians to withdraw back to their bridgehead. The 4th horse artillery battery under Lieutenant Colonel Józef Bem particularly distinguished itself, covering the retreat of the Polish forces.