Creation of the Inundation Inundation, Gibraltar

map of morass, marshy area in front of gates of gibraltar, later converted inundation (north left of map). lines around spanish trenches dug in 1704 siege of gibraltar.

prior creation of inundation, principal access gibraltar via narrow strip of land between morass , cliff face of rock. during thirteenth siege of gibraltar, spanish had managed dig trenches along strip of land reach within 600 feet (180 m) of walls of gibraltar. redan or flèche built in front of town s landport gate during siege overlook morass , provide additional defence.

oliver cromwell had suggested in previous century canal dug across isthmus make gibraltar island. although idea not taken up, british commanders decided make morass more substantial obstacle , in 1735, dug out , flooded form pear-shaped lake connected sea via short channel. water in inundation held 4 ft (1.2 m) high dike, allowed 5 ft (1.5 m) high tide replenish it, though arrangement changed in 19th century. inundation restricted landward access gibraltar 2 narrow passages on either side of water, 1 below sheer cliff face of rock , other, used main road gibraltar (now winston churchill avenue), forming narrow causeway known strand between sea , landport gate. according late 18th-century author, inundation measured 200 yards (180 m) in length 60 yards (55 m) broad , man-height in depth.

to further restrict access, british built 2 defended positions on either side of northern end of inundation, not guard against surprise attack prevent desertion disgruntled members of gibraltar s garrison. advance guard room built on east side on foundations of earlier spanish fortification had controlled movement across strip of land adjoining morass. after william green became gibraltar s senior engineer in 1761, had advance guard room (renamed forbes barrier) more heavily fortified , had bayside barrier constructed on other side control access causeway. both surrounded palisades.

in 1760s, line of spiked chevaux de frise constructed across top , bottom ends of inundation. ditches twelve feet wide , 3 feet deep dug across inundation on both sides of chevaux de frise if lake ever dried out still serve barrier. barrier constructed @ south end of inundation, , stakes driven bed of lake serve underwater obstacles. unnamed correspondent london chronicle wrote on 19 april 1762: thro middle [of inundation] have run chevaux de frize, lined plates of iron, , studded iron spikes, 1 row pointing towards spain, , other towards garrison, prevent desertion. 5 feet high, sunk in mud, , spikes above water; clasping hands together, fingers extended , backs up, have exact idea of them. through inundation enemy must march come near us, causeway narrow, , when tide @ lowest ebb, thirty men not march a-breast upon beach , causeway; upon point can bring above 300 cannon , mortars bear, besides wall-pieces , small arms. iron hoops , many other articles entangle , obstruct enemy scattered across bottom of inundation.

above inundation, rock of gibraltar rose in series of scarped steps had been fortified defensive walls, gun batteries , rock-cut trenches. causeway enfiladed king s, queen s , prince s lines, willis battery above lines , still further batteries higher on rock, enemy attempting cross met hail of fire several directions. in addition, guns of grand battery facing isthmus trained on causeway, b. cornwell recorded: guns on battery reason kept charged round , grape shot, , levelled man-height surface of isthmus; artillery guard kept @ battery, , lighted match ready apply cannon in case of necessity. british clergyman, william robertson, commented in 1845 account of visit gibraltar while crossing causeway, inexperienced eye struck terrible appearance of batteries command it, bristling cannon, above , around. spanish called landward approach gibraltar el boca de fuego, mouth of fire.