grade ▁and ▁engaged ▁some ▁d ive ▁bom bers , ▁claim ing ▁one ▁Stu ka ▁shot ▁down . ▁During ▁the ▁first ▁attack , ▁the ▁Y ug oslav s ▁claimed ▁fifteen ▁German ▁aircraft ▁shot ▁down ▁and ▁lost ▁five ▁of ▁their ▁own , ▁with ▁six ▁more ▁badly ▁dam aged . ▁The ▁pil ots ▁of ▁J G ▁ 7 7 ▁claimed ▁ten ▁Y ug oslav ▁machines ▁shot ▁down ▁and ▁another ▁six ▁destroyed ▁on ▁the ▁ground . ▁On ▁his ▁return ▁to ▁base , ▁the ▁commander ▁of ▁the ▁ 5 1 st ▁F ighter ▁Group ▁was ▁rel ieved ▁of ▁his ▁command ▁for ▁failure ▁to ▁take ▁action . ▁The ▁first ▁wave ▁hit ▁the ▁Bel grade ▁power ▁station , ▁the ▁post ▁office ▁including ▁te legraph ▁and ▁postal ▁services , ▁the ▁headquarters ▁of ▁the ▁Ministry ▁of ▁Army ▁and ▁Navy , ▁the ▁Y ug oslav ▁Supreme ▁Command ▁building , ▁the ▁military ▁a cademy , ▁the ▁royal ▁palace ▁at ▁D ed in je , ▁the ▁royal ▁guard ▁bar ra cks ▁at ▁Top č ider , ▁the ▁g endar mer ie ▁command ▁headquarters , ▁and ▁the ▁air port ▁at ▁Z em un , ▁among ▁other ▁targets . ▁ ▁Im medi ately ▁after ▁the ▁first ▁wave , ▁King ▁Peter , ▁the ▁Government ▁of ▁Y ug oslav ia ▁and ▁the ▁Y ug oslav ▁Supreme ▁Command ▁left ▁Bel grade ▁and ▁retre ated ▁to ▁Y ug oslav ia ' s ▁mountain ous ▁interior ▁with ▁the ▁intention ▁of ▁going ▁into ▁ex ile . ▁The ▁second ▁wave ▁of ▁German ▁aircraft ▁arrived ▁over ▁Bel grade ▁about ▁ 1 0 : 0 0