Columbia subject headings:
Harvard subject headings:
Fortification--Portugal--Lisbon--History--19th century.
Lisbon (Portugal)--Defenses--History--19th century.
Napoleonic Wars, 1800-1815--Campaigns--Portugal.
Princeton subject headings:
Fortification--Portugal--Lisbon--History--19th century.
Lisbon (Portugal)--Defenses--History--19th century.
Napoleonic Wars, 1800-1815--Campaigns--Portugal.