The Spanish lines consisted of a continuous series of fortifications anchored at either end by two substantial forts. Lieutenant Colonel Thomas James of the Royal Artillery, writing in his 1771
History of the Herculean Straits, provided a detailed description of each of the forts and bastions. is on the left-hand side of the map, and Fort St. Philip is on the right-hand side. In between are the bastions of Santiago, San Carlos, San José, Santa Mariana and San Benito. At the west end, Fort San Felipe (Spanish:
Fuerte de San Felipe) had 28 gun positions with a ditch and a bastion trace in the gorge (rear) of the fort. Its broad structure gave the Spanish gunners a wide
arc of fire across the
Bay of Gibraltar and provided a direct line of fire into the town and the British
Devil's Tongue Battery located along the
Old Mole. Two demi-bastions and a curtain wall were situated at the rear of the fort while storehouses and guard-houses stood alongside it. A solid stone sea wall ran along the east side of the fort. A ditch, filled from the sea and controlled via a sluice gate, provided an additional obstacle. According to James, the normal garrison of the fort was one captain, one subaltern and fifty men, though it could accommodate six hundred.
Fort Santa Barbára (Spanish:
Fuerte de Santa Barbára) stood at the eastern end of the line. Its pentagonal structure was aimed like an arrowhead south at Gibraltar and supported 24 gun positions, with a bastion trace in the gorge, a dry ditch, a covered way and a
glacis. The two eastern sides of the fort looked out over the
Mediterranean Sea, while the south-facing side enfiladed part of the eastern side of Gibraltar and the isthmus. In between the two forts, the line of fortifications took the form of a continuous
redan line, with a
curtain wall interrupted by a series of triangular bastions. The lines were constructed in a straight line at the eastern end but bulged out at the western end, where it was intended to build an
entrenched camp to hold an army while it prepared to launch an attack on Gibraltar, though the rear portion of this structure was never completed. The five bastions were named (in order from west to east) after
St. James (
Santiago),
St. Charles (
San Carlos),
St. Joseph (
San José), Saint Mariana (
Santa Mariana) and
Saint Benedict (
San Benito). ==Use==