▁ 1 9 3 8 ▁where ▁he ▁successfully ▁completed ▁a ▁course ▁of ▁studies , ▁and ▁was ▁promoted ▁to ▁head ▁of ▁the ▁local ▁SD ▁office ▁in ▁Mün ster ▁in ▁ 1 9 3 9 . ▁During ▁the ▁invasion ▁of ▁the ▁Netherlands ▁on ▁ 1 0 ▁May ▁ 1 9 4 0 , ▁J äger ▁was ▁named ▁commander ▁of ▁Einsatz k omm ando ▁ 3 , ▁a ▁unit ▁of ▁Einsatz gruppe ▁A . ▁Additionally , ▁ ▁J äger ▁was ▁promoted ▁to ▁the ▁rank ▁of ▁Stand arten führ er , ▁the ▁equivalent ▁of ▁a ▁colon el ▁in ▁the ▁German ▁army , ▁the ▁same ▁year . ▁ ▁Mass ▁mur ders ▁in ▁eastern ▁Europe ▁ ▁J äger ▁was ▁instrument al ▁in ▁the ▁brut al ▁and ▁system atic ▁destruction ▁of ▁the ▁Jewish ▁community ▁of ▁Lith u ania . ▁From ▁July ▁ 1 9 4 1 ▁until ▁September ▁ 1 9 4 3 ▁J äger ▁served ▁as ▁commander ▁of ▁the ▁SD ▁Einsatz k omm ando ▁ 3 a , ▁a ▁sub - unit ▁of ▁Einsatz gruppe ▁A ▁under ▁Franz ▁Walter ▁St ah le cker , ▁in ▁Ka unas . ▁ ▁Under ▁J äger ' s ▁command , ▁the ▁Einsatz k omm ando , ▁with ▁the ▁help ▁of ▁Lith u ani ans , ▁shot ▁Jewish ▁men , ▁women ▁and ▁children ▁ind isc rimin ately . ▁ ▁It ▁perpet r ated ▁the ▁N inth ▁Fort ▁mass ac res ▁of ▁November ▁ 1 9 4 1 . ▁ ▁During ▁this ▁time , ▁reports ▁detail ing ▁calculated ▁acts ▁of ▁mass ▁murder ▁were ▁rout in