It did not engage in combat until September 3, covering the area of Łomża, and sporadically attacking Wehrmacht units advancing from East Prussia.

In the evening of September 9, the Brigade engaged in heavy fighting, trying to recapture the town of Brok, with its bridge over the Bug River.

The Poles managed to capture eastern part of the town, but then their advance was stopped.

On September 11, the Brigade withdrew towards Zambrów, next day it joined forces with Suwalska Cavalry Brigade, creating the so-called 'Group' of General Zygmunt Podhorski: "Zaza Cavalry 'Division'" ("Zaza" after "Zygmunt").

After the Soviet invasion of Poland, remnants of the Brigade fought both Wehrmacht and Red Army troops, capitulating on October 6.