Fortifications raise the time and cost of capturing a place. A prolonged siege allows relief forces, peace negotiations, or disease to change the attacker's prospects. Defenders at least have buildings and some sanitary facilities, while attackers occupy temporary camps exposed to mud and poor conditions. Cartagena's successive works required the British to overcome several lines and made limited Spanish manpower harder to dislodge. The illustrated colonial fort is described as using star-fort principles on a modest scale, with accommodation largely built into its walls.
Notable Point · 1:07:22-1:11:30
Fortifications are designed to buy time
Cartagena's defenses illustrate that forts need not be impregnable: they raise an attacker's cost and delay it until weather, disease, or relief changes the campaign.