istol ▁consisted ▁of ▁ 8 0 ▁ra iders , ▁but ▁as ▁they ▁approached ▁over ▁Dor set ▁they ▁were ▁broken ▁up ▁by ▁the ▁well - direct ed ▁AA ▁guns ▁and ▁night - fig h ters : ▁two ▁were ▁shot ▁down , ▁the ▁others ▁scattered ▁their ▁bomb s ▁in ▁open ▁country , ▁and ▁one ▁reached ▁the ▁city . ▁ ▁Operation ▁D iver ▁AA ▁Command ▁had ▁plenty ▁of ▁warning ▁that ▁the ▁Germ ans ▁were ▁developing ▁V - 1 ▁flying ▁bomb s ▁to ▁use ▁against ▁the ▁UK , ▁and ▁had ▁detailed ▁plans ▁in ▁place ▁( Operation ▁D iver ). ▁This ▁included ▁def ences ▁for ▁Br istol ▁compr ising ▁success ive ▁defence ▁bel ts ▁across ▁the ▁anticip ated ▁flight ▁paths , ▁consisting ▁of ▁S / L s ▁and ▁L AA ▁guns , ▁then ▁H AA ▁and ▁L AA ▁guns , ▁followed ▁by ▁Bar rage ▁bal lo ons ▁and ▁Z ▁B atter y ▁rock ets ▁before ▁the ▁miss iles ▁reached ▁the ▁Br istol ▁G DA . ▁The ▁V - 1 s ▁began ▁arriv ing ▁on ▁ 1 3 ▁June ▁ 1 9 4 4 , ▁a ▁week ▁after ▁the ▁Al lies ▁had ▁launched ▁their ▁invasion ▁of ▁Norm andy ▁on ▁D ▁Day . ▁Operation ▁D iver ▁was ▁put ▁into ▁effect , ▁but ▁the ▁off ensive ▁against ▁Br istol ▁never ▁got ▁under ▁way , ▁because ▁US ▁forces ▁quickly ▁captured ▁the ▁launch ▁sites ▁on ▁the ▁Cher bourg ▁pen ins ula . ▁▁ ▁The ▁first ▁V - 1 ▁off ensive ▁was ▁concentr ated ▁against ▁London , ▁and ▁continued ▁until ▁the ▁launch ing ▁sites