Initially composed of 319 officers and 3,437 soldiers, Kopański's brigade soon grew to roughly 5,000 men. Among the distinctive features of the unit was the high morale of the soldiers, all volunteers. In addition, roughly 25 percent were educated, a thing uncommon in European armies of the time. Kopański continued to train his men in mountain warfare, but also in warfare in desert conditions, completely alien to the Polish soldiers. In August 1941, the brigade was moved by sea from Palestine to the besieged town of Tobruk, where the unit took part in the final four months of the siege. After the siege was lifted on December 10, the brigade joined British forces in their pursuit of the withdrawing Italo-German armies and fought in the Battle of Gazala.