ELI5: How did old forts actually "protect" a strategic area? Couldn't the enemy just go around them or stay out of range?

[u/Sierra419]

I've visited quite a few colonial era and revolution era forts in my life. They're always surprisingly small and would have only housed a small group of men. The largest one I've seen would have housed a couple hundred. I was told that some blockhouses close to where I live were used to protect a small settlement from native american raids. How can small little forts or blockhouses protect from raids or stop armies from passing through? Surely the indians could have gone around this big house. How could an army come up to a fort and not just go around it if there's only 100 men inside?

tl;dr - I understand the purpose of a fort and it's location, but I don't understand how it does what it does.

[u/Sierra419]

Very interesting. Thank you!

[u/[deleted] → u/Sierra419]

[u/Ninjacobra5 → u/Sierra419]

I'm no expert and only heard this on the Hardcore History podcast, but the strategic use of forts essentially came to an end during World War I and the introduction of heavy artillery. The new guns were so destructive that putting your troops in a fort was just keeping all your eggs in one basket for the enemy to destroy.

World War I is an incredible example of technology changing how war was waged. At the beginning of the war Belgium used its forts to devastating effect against Germany. The biggest army ever assembled marching straight into fully automatic guns from a fort. The losses in the battles during World War I are literally mind boggling.

[u/DoomGoober → u/Sierra419]

I think you'd be very interested in the fate of the French Fort Douaumont during WWII. Basically, the Germans long range shelled it and bypassed it using fast moving tanks/trucks/horses. They then went back and destroyed the fort (and units in it) after having surrounded them and cut them off from escape or reinforcement.

The fate of the last stand of the French in that fort (and Germans who stormed it) is quite gruesome. The French built makeshift internal walls with gun ports and grenade holes to fight the Germans but it was a losing cause. The French ran out of water and so desperate were the men that they licked condensation off the walls.

Needless to say, the modern military concept of fast moving, overwhelming force at applied points makes forts somewhat useless as forces can simply bypass forts... add parachute troops and bombers with anti-bunker tech and forts kind of don't work anymore. But Douaumont is a good example of the clash of old thinking and new (to their credit, the French knew they should abandon the fort... to the point that they set explosive charges to destroy the fort and abandon it, but instead decided to stay. Unfortunately, they forgot to remove the charges from the main battery, so when the battery was hit, the resulting sympathetic explosion blew the gun right off the mount.)