How a Siege Works, Circa 1700
The Mechanics of a Siege
Military engineers built forts for several reasons: to protect cities, to protect strong points from falling into enemy hands, to be a visible symbol of governmental authority. If a fort could not be taken by surprise, an attacking party had to take the fort by force. The process of surrounding an enemy’s strong point and slowly cutting off all contact with the outside world is known as a siege. Sieges go back to Biblical times, but the principles were formulated by Sébastien le Prestre de Vauban (1633-1707), a French military engineer who served in the armies of Louis XIV. He created a very formal, disciplined science, and his plan was maddeningly simple. First a trench parallel to the fort was dug out of gun range so the attackers could move in supplies and troops. Sappers—crews of trench diggers—then dug zigzag trenches toward the fort; the zigzag pattern made it more difficult for defenders to hit the trenches. Next the sappers dug a second parallel that included some batteries for shelling the fort. Additional zigzag trenches and parallels would be dug until the attackers were in a position to concentrate their fire at one point on the fortification to breach its walls. The fortress would then have no alternative but to surrender or be stormed. Conducting a textbook perfect siege did not always result in success, for the fort’s defenders would not have been idle. They would fire cannon at the sappers. Often they dug counter trenches out from the fortress and planted mines to blow up the work of the attackers. And they would send out nighttime raiding parties, too.
1st Parallel
Military engineers, called sappers, construct trenches and raise earthworks to protect the attacking forces.
Line of attack
Mortar fire destroys cannon and drives defenders to cover; siege lines prevent supplies from reaching the fort.
2nd Parallel
Siege guns destroy cannon and weaken fort walls.
3rd Parallel
Siege guns breach the walls, enabling attacking forces to enter the fort.
A Fort’s Defenses
Attackers OUTER WORKS Glacis Covered Way Moat Ravelin INNER FORT Moat Parapet Scarp Rampart Magazine
The Cubo Line originally stretched from the Castillo to the San Sebastian River. It was strengthened and rebuilt repeatedly by both the Spaniards and the British. The city gate, a part of the line, was built in 1808, only a few years before the United States took control of Florida.
His concerns were genuine, for work on the vaults had to stop as the war dried up construction funds. The fort was left in a strangely irregular shape. The east side, including San Carlos bastion, was at the new height, but all others were several feet lower. The old rooms still lined three sides of the courtyard.
On June 13, 1740, seven British warships dropped anchor outside the inlet. The long-expected siege of St. Augustine had begun. Montiano hastily sent the news to Havana and with it a plea for help. He had 750 soldiers and the 120 or more sailors who manned the galliots. Rations would last only until the end of June.
The attackers numbered almost 1,400, including sailors and Indian allies. While the warships blockaded the harbor on the east, William Palmer came in from the north with a company of Highlanders and occupied the deserted outpost called Fort Mose. Oglethorpe landed his men and guns on each side of the inlet and began building batteries across the bay from the Castillo.
Montiano saw at once that all the English positions were separated from each other by water and could not speedily reinforce one another. Fort Mose, at the village of the black runaways a couple of miles north of the Castillo, was the weakest. At dawn on June 26 a sortie from St. Augustine hit Fort Mose, and in the bloodiest action of the siege scattered the Highlanders and burned the palisaded fortification. Colonel Palmer, veteran of Florida campaigns, was among the dead.
As if in revenge, the siege guns at the inlet opened fire. Round shot whistled low over the bay and crashed into fort and town. Bombs from the mortars soared high—deadly dots against the bright summer sky—and fell swiftly to burst with terrific concussion. The townspeople fled, 2,000 of them, some to the woods, others to the covered way where Castillo walls screened them from the shelling.
For 27 nerve-shattering days the British batteries thundered. At the Castillo, newly laid stones in the east parapet scattered under the hits, but the weathered old walls held strong. As one Englishman observed, the native rock “will not splinter but will give way to cannon ball as though you would stick a knife into cheese.” One of the balls shot away a gunner’s leg, but only two men in the Castillo were killed during the bombardment.
The heavy guns of San Marcos and the long 9-pounders of the fast little galliots in the harbor kept the British back. Despite the bluster of the cannonades, the siege had stalemated. Astride the inlet, Oglethorpe and his men battled insects and shifting sand on barren, sun-baked shores, while Spanish soldiers in San Marcos, down to half rations themselves, saw their families and friends starving. On July 6 Montiano wrote, “My greatest anxiety is provisions. If these do not come, there is no doubt that we shall die in the hands of hunger.”
The very next day came news that supplies had reached a harbor down the coast south of Matanzas. Shallow-draft Spanish vessels went down the waterway behind Anastasia Island, fought their way out through Matanzas Inlet and, hugging the coast, went to fetch the provisions. Coming back into Matanzas that same night, they found the British blockade gone; they reached St. Augustine unopposed.
Oglethorpe made ready to assault the Castillo despite the low morale of his men. His naval commander, however, was nervous over the approach of the hurricane season and refused to cooperate. Without support from the warships, Oglethorpe had to withdraw. Daybreak on July 20—38 days since the British had arrived at St. Augustine—revealed that the redcoats were gone.
This 1763 engraving shows the finished Castillo after all the bombproof vaults and a new ravelin had been built.
Beyond the military aspects, which were so vital to the decision to establish St. Augustine, the city had become a vibrant community of soldiers, their families, government officials, and shopkeepers. Religion and the church played an important part in the life of the community. This page from a Roman Catholic missal. printed in 1690, is open to the service for Easter The right-hand column recounts the story of how the Marys went to the tomb and found it empty.