The Brigade was formed in early June 1939, when the Polish Minister of Military Affairs, General Tadeusz Kasprzycki, gave order to transform the 1st Regiment of Mounted Rifles from the Garwolin garrison into a motorized unit.
It stayed there until September 3 as a reserve of the Commander-in-Chief of the Polish Army, then was ordered to prepare the defence of the Vistula river line between Dęblin and Solec.
The Polish forces decided to attack the town of Tomaszów Lubelski; the offensive was carried out in the morning of September 17 by Warsaw Armoured Motorized Brigade, which managed to catch the German XXII Corps by surprise.
On September 19, another Polish attack did not succeed, and one day later, after fierce fighting and destruction of large part of equipment, General Piskor decided to surrender.
He himself was not caught by the Germans, also hundreds of Brigade's soldiers managed to escape to Hungary and later to Great Britain, where they joined the Polish 1st Armoured Division of General Stanisław Maczek.