▁were ▁claimed ▁by ▁AA ▁guns ▁and ▁f igh ters . ▁In ▁addition ▁to ▁aircraft ▁shot ▁down ▁claimed ▁by ▁the ▁g unn ers , ▁they ▁caused ▁many ▁losses ▁to ▁German ▁aircraft ▁which ▁went ▁un seen ▁from ▁the ▁British ▁side . ▁For ▁example , ▁on ▁ 2 8 ▁July ▁two ▁J unk ers ▁ 8 8 ▁from ▁the ▁same ▁German ▁formation ▁were ▁dam aged ▁over ▁the ▁Th ames ▁Est ury ▁by ▁anti - air craft ▁fire ▁but ▁managed ▁to ▁return ▁to ▁occupied ▁Europe ; ▁however , ▁both ▁crash ed ▁on ▁landing ▁and ▁were ▁written ▁off . ▁Al most ▁all ▁the ▁crew ▁of ▁both ▁aircraft ▁were ▁killed ▁or ▁wounded . ▁ ▁One ▁of ▁the ▁less ons ▁the ▁Germ ans ▁lear nt ▁during ▁the ▁Battle ▁of ▁Britain ▁was ▁that ▁day ▁bom bers ▁needed ▁to ▁fly ▁in ▁tight ▁formation ▁for ▁mut ual ▁protection ▁against ▁f igh ters . ▁However , ▁the ▁t ighter ▁form ations ▁made ▁easier ▁targets ▁for ▁ground ▁based ▁guns ▁and ▁were ▁more ▁vulner able ▁to ▁AA ▁fire . ▁On ▁ 8 ▁September ▁a ▁formation ▁of ▁ 1 5 ▁D orn ier ▁Do ▁ 1 7 s ▁fle w ▁along ▁the ▁Th ames ▁at ▁ 1 5 , 0 0 0 ▁feet . ▁The ▁opening ▁sal vo ▁from ▁a ▁tro op ▁of ▁four ▁ 3 . 7 - inch ▁guns ▁of ▁ 2 8 ▁AA ▁B de ▁brought ▁down ▁the ▁three ▁leading ▁aircraft ▁and ▁scattered ▁the ▁others ▁in ▁dis order ; ▁they ▁j ett ison ed ▁their ▁bomb s ▁as ▁they ▁escaped . ▁On ▁ 1