▁Techn ical ▁Department . ▁Its ▁facilities ▁were ▁greatly ▁expanded ▁from ▁ 1 9 3 9 - 1 9 4 1 ▁due ▁to ▁the ▁military ▁bu il dup ▁prior ▁to ▁the ▁start ▁of ▁the ▁Pacific ▁War . ▁ ▁The ▁facilities ▁consisted ▁of ▁seven ▁plants : ▁ <0x09> Sm ok eless ▁pow der ▁for ▁rock ets ▁and ▁art illery ▁ <0x09> N it ro cell ul ose ▁and ▁mixed ▁ac ids ▁production ▁ <0x09> Vari ous ▁ac ids ▁and ▁hydro gen ▁production ▁ <0x09> Des ign ▁and ▁Engineering , ▁prototype ▁development ▁ <0x09> Machine ▁gun ▁am mun ition ▁production , ▁sol vent ▁recovery ▁ <0x09> N aval ▁art illery ▁shell s ▁ <0x09> N it rog ly cer in ▁production ▁ ▁On ▁the ▁night ▁of ▁July ▁ 1 6 , ▁ 1 9 4 5 ▁the ▁facilities ▁were ▁attacked ▁by ▁ 1 3 8 ▁B - 2 9 ▁Super fort ress ▁bom bers ▁of ▁the ▁USA AF ▁ 2 0 th ▁Air ▁Force , ▁ 3 1 4 th ▁Bomb ard ment ▁Wing ▁which ▁dropped ▁a ▁total ▁of ▁ 1 1 6 3 ▁tons ▁of ▁inc endi ary ▁bomb s ▁on ▁the ▁city , ▁destroy ing ▁most ▁of ▁the ▁city ▁ ▁center . ▁Only ▁ 5 % ▁of ▁the ▁capacity ▁of ▁the ▁Imperial ▁Japanese ▁Navy ▁Am mun ition ▁Ar sen al ▁was ▁affected , ▁as ▁the ▁bomb ing ▁was ▁concentr ated ▁on ▁Hir ats uka ' s ▁civil ian ▁population ▁center , ▁rather ▁than ▁the ▁military ▁indust ries ▁located ▁on ▁the ▁out sk ir ts