In 1702 Carolina attacked St. Augustine. The attack was not successful and through a fifty day seige the Castillo held. However the weakness of the city was revealed when the city was burned to the ground by the Carolinians before their departure from St. Augustine. The Castillo guns could not stop invaders from entering the city. This conflict between the English and the Spanish would last til 1714.
On June 4, 1704 Governor Jose de Zuniga and the royal officials (the accountant and the treasurer) held a council where it was determined to fortify the area between the Castillo de San Marcos and the San Sebastian river. The line would be a series of redoubts on a cleared field connected with palisades and a ditch. Infantry would garrison the redoubts. Six redoubts were built. By October 26, 1705 the redoubts had been finished.
Lines of Defense A second line was started by Governor Corcoles that would become the Hornwork. This line (basically where Mission Street is today) would in part replace the Cubo line as a forward line of defense. (Eventually a third line of defense the Fort Mose line would be built from Fort Mose on the North River to the San Sebastian. It was never properly finished.)
Design of the Cubo Line There is no record of this line being called the "Cubo" line until 1737. The word cubo defines round, square, or polygonal towers placed in ancient and medieval defensive walls to protect their flanks. The Engineer Antonio de Arredondo recorded the design of the works as a palisade approximately 240 yards long beginning at the west counterscarp of the Castillo and ending at the junction with the Rosairo line. From the Rosairo line to the San Sebastian river the line was earthwork and yucca for another 495 yards. The only opening in the 733 yard line was a 5 1/2 foot gate 10 yards from the Castillo counterscarp.
By 1737 the hornwork had disappeared and the Cubo was the only northern defense line. Engineer Pedro Ruiz (April 1738) started working again on the Cubo line. The palisade was eliminated and it became an earthwork for its full length. The moat was cleaned out and yucca was planted along the scarp. The gate was shifted to St.George Street. The gates name was the La Leche gate which was 7 1/2 feet wide
After Oglethorp's attack the Cubo line was finished and improved. The sod parapet was 2 3/4 feet thick and a solid palisade revetted the scarp. The redoubts were sod redoubts with walls 8 1/4 feet thick with enough space for 6 cannon. The moat was 733 years long 11 feet wide and 5 1/2 feet deep.
The British Period Governor Tonyn decided to restore the 3 defensive lines of St. Augustine. Shortly before Feb 1776 the Cubo Line was repaired. Tonyn describet it as "the North curtain of this town, it is the inner line that runs from the Fort west to St. Sebastian Creek. The repairs included putting pine logs in the earth work and constructing a palisade to the west of the Cubo Redoubt. The Surveyor J. Purcell in 1777 recorded the Cubo line as extending from the Fort to St. Sebastian Creek for 902 yards. The portion of the line between the Santo Domingo Redoubt and the Fort was bent slightly to the north.
The Second Spanish Period While improvements had been recommended by Engineer Mariana de la Rocque the money was lacking for improvements. The improvements in 1791 only consisted of the removal of the brush that was growing on the defense lines. By 1797 Engineer Pedro Diaz Berrio could only say that the redoubts and curtains around the city as well as the Honabeque and Fort Mose lines were non-existent.
In 1797 finally work was begun. The gun platforms of the three redoubts were rebuilt for artillery and the moat was cleared of soil that had fallen into it. By 1804 Engineer Manuel de Hita could say that the Cubo Line was not in bad condition. He requested that it be rebuilt with stone. The work stopped again for lack of money.
In 1808 the entrenched line was straightened. The earth parapet getween the gate and the San Sebastian River was heightened. The gate was rebuilt in masonry. Hita was transfered to Santo Domingo in 1811 and no engineer was sent in replacement.
In 1818 work was again done on the Cubo line with the money running out once again. Convict labor was used to repair the walls.
On April 20, 1820 Ramon de la Cruz became the resident engineer. The Cubo Redoubt was now a square but had a good parapet. The line of dirt extended 917 yards faced with a moat 40 1/3 feet wide and 4 feet 7 inches deep from the San Sebastian to the Castillo. The scarp was only a ridge of sand and the parapet shapeless because of water erosion. By June 4, 1821 the line had been improved. The parapet was 2 3/4 to 3 3/4 feet thick on top. 19 1/4 feet thick at the base which formed a sloping scarp with a berm to the bottom of the moat. A log revetment 8 1/4 feet high and 5 3/8 by 7 inches thick ran the whole length of the line.
The Tolomato redoubt had an embrasure in each flank and two on its face with a wooden guardhouse. The Middle Redoubt had a thatched hut. The middle redoubt had two gun platforms.
The American Period The defense fell in disuse again in the American period. By Jul7 3, 1827 Lieutenant Harvey Brown was in U. S. District court to halt the city from tearing down the old City gate. The project was halted and the damage repaired.
In a 1833 report Engineer Lieutenant Stephen Tuttle noted the parapet in ruins the palisade south and west of the Cubo redoubt gone. The leaves of the gate had been removed and the bridge at the city gate was gone replaced by a stone causeway paid for by the City of St. Augustine.
In a April 1842 survey engineer H. W. Benham noted that the moat was between zero and one foot depth. The field on both sides of the depression rose 3 to 4 feet and on the north and south banks there were large mounds of earth 6 feet above the floor of the depression.
By 1857 the ground between the ruined parapet and the house of Bartolo Oliveros was so low that it flooded with rain water. The eastern portion of the Cubo line became a drainage ditch.
Captain Post began a survey of the line on December 1, 1877. He laid a marble monument at the east end near the fort to mark the end of the line. He with difficulty surveyed the east end of the line while the western part of the line was more visable.
On January 13, 1890 the Secretary of War granted license to the Jacksonville, St. Augustine and Halifax River Railway Co. to place tracks over the west end of the moat and by July 11, 1890 it was converted into a right-of-way by an act of Congress. Another Act of Congress on September 26, 1890 gave the St. Augustine Street Railway Co. a right-of-way along Orange Street and the western and southern sides of the Castillo grounds. On May 23, 1891 the Secretary of War granted permission to the St. Augustine City Council for the paving of Orange Street. On February 22, 1907 land was given to the School board with the right to recover for the site of a school (See Orange Street School)