The Lines of Torres Vedras
in secret by the British to protect Lisbon from land-based attack,
the lines of Torres Vedras stretched from the Atlantic coast to
the banks of the impassable Tagus River.
took 10,000 labourers a year to complete and cost some 100,000 pounds.
That figure is not surprising in that the triple defensive lines
consisted of more than 100 redoubts packed with almost 450 cannons.
than 25,000 troops, mainly militia, garrisoned the lines and signal
stations on dominant mountain tops meant a message could be transmitted
from one end of the positions to the other in under seven minutes.