Complex sentence: The second battalion was established in February 1943 when the regiment's strength reached 700 men, of whom 300 were anti-communists from Soviet territory; and the unit was redesignated as the "SS-Sonderregiment Dirlewanger".
Split into simpler sentences: The second battalion occurred in February 1943 when the regiment's strength reached 700 men. The unit was redesignated as the "SS-Sonderregiment Dirlewanger".