▁le ve led ▁by ▁U . S . ▁Army ▁engine ers ▁and ▁then ▁was ▁built ▁up ▁with ▁thick ▁layers ▁of ▁steel - re in for ced ▁concrete ▁into ▁a ▁massive ▁structure ▁roughly ▁res emb ling ▁a ▁batt les hip , ▁ ▁long , ▁ ▁wide , ▁and ▁with ▁a ▁top ▁deck ▁ ▁above ▁water ▁at ▁mean ▁low ▁t ide . ▁The ▁ ▁M 1 9 0 9 ▁guns ▁and ▁their ▁two ▁custom ▁built ▁M 1 9 0 9 ▁tur rets , ▁named ▁B atter ies ▁Marshall ▁and ▁Wilson , ▁were ▁delivered ▁and ▁installed ▁by ▁ 1 9 1 6 . ▁The ▁M 1 9 0 9 ▁guns ▁were ▁spe cially ▁designed ▁for ▁Fort ▁Dr um ▁and ▁were ▁not ▁deployed ▁elsewhere . ▁The ▁secondary ▁ ▁M 1 9 0 8 M II ▁guns ▁on ▁M 1 9 1 0 ▁ped est al ▁mount s ▁in ▁cas em ates , ▁B atter ies ▁Roberts ▁and ▁McC rea , ▁were ▁installed ▁the ▁same ▁year . ▁ ▁Search light s , ▁anti - air craft ▁batter ies , ▁and ▁a ▁ ▁lattice - style ▁fire ▁control ▁tower ▁were ▁mounted ▁on ▁the ▁fort ' s ▁upper ▁surface . ▁The ▁living ▁qu arters ▁for ▁the ▁approximately ▁ 2 4 0 ▁officers ▁and ▁en list ed ▁men ▁along ▁with ▁the ▁power ▁gener ators , ▁plot ting ▁rooms ▁and ▁am mun ition ▁mag az ines ▁were ▁located ▁deep ▁inside ▁the ▁fort . ▁ ▁B atter y ▁Marshall ▁was ▁named ▁for ▁Brig ad ier ▁General ▁William ▁Louis ▁Marshall , ▁Civil ▁War ▁Medal