In the summer of 1943, the leadership of the Slovenian national liberation movement predicted that Italy would soon withdraw from the war. Therefore, it gathered all the partisan brigades in the Ljubljana region in order to seize as many weapons and military materials as possible from the Italian army. When the surrender of Italy was announced on September 8, 1943, the Headquarters of the National Liberation Army of Slovenia ordered immediate pressure on the Italian units in the garrisons to surrender and hand over tens of thousands of pieces of weapons, including heavier arms. At the same time, the leadership ordered the general mobilization of men into the partisan army. Less planned, the population in the Primorska region launched an uprising that led to the collapse of Italian rule and the massive, in many places spontaneous, establishment of partisan units. The result of this process was the rapid numerical growth of the partisan army – from 6,000 to around 25,000 members. Organizational development barely kept up. The number of brigades, basic combat units, increased from 6 to 13 in the Ljubljana Province and from 9 in the Primorska region with the newly established ones.