What's the "lesson" of each modern war?

I think the lesson learned with Korea is that to “win” you essentially need to be there forever.

The lesson from the recent Afghan-Taliban “war” of 2021:
Pay attention to the lesson from the last two wars in Afghanistan.

That and the lesson of both wars the fact that Industrial nations could aborb horrific losses in men and material and continue fighting. One of the things forgotten is that in WW1, “home by Christmas” was heavily predicated upon the fact that the General Staffs knew that the losses would be heavy, they expected that the armies would have fought themselves to exhaustion by the end of the year, That is indeed what happened. What they did not expect was just how quickly industry would be able to make good losses. In WW2, both Germany and Japan ended tha war having more equipment then men to operate them.

In short, Afghanistan’s strategic value isn’t worth the cost. It only becomes a place of strategic importance when it’s a buffer between two superpowers or when it becomes a safe haven for transnational militias. The lesson for empires is, a) don’t let the paranoia suck you in; b) once the militias are vanquished, be done with the place b/c nation building is hopeless.

The US has kept troops in Europe and Japan since the end of WWII, as well.

While this has been pointed out several times, obviously the forces in Germany and Japan are not there constantly trying to fight back a portion of the populations of Germany and Japan.

Oooops

I phrased that in a way that implied what I just said had been said several times. It didn’t mean it that way, and came across like I was peevish. What I meant was the occupation had been mentioned, not the point that it wasn’t an occupation of a hostile population. Sorry.

Absolutely. That should be a given that there is a world of difference between decades of bases troops in an ally and fighting a war. I was questioning why @msmith537 would make that a point of the Korean War.

We are all good.

Well, the way I see it, the Korean War is at best considered a “tie” (or at worst, technically “still ongoing”). But 70 years later, South Korea is a modern advanced democratic nation while North Korea is a backward craphole ruled by a dictator. But as you correctly pointed out, for that to happen, on some level South Korea had to want the US there for 70 years keeping the peace.

So to take a lesson from this, I might look at what worked in Korea that didn’t work in Vietnam or Afghanistan.

Actually I’d argue that at the time, the lesson was that naval forces were still vulnerable to attack aircraft. Four of the six British ships sunk were sunk by old-school bombs (HMS Antelope, HMS Ardent, HMS Coventry and RFA Sir Galahad), not Exocet missiles (HMS Sheffield, SS Atlantic Conveyor).

More like a small number of Western professional soldiers will beat a whole lot of lesser-equipped draftees from other countries. It wasn’t nearly so much the high tech gizmos that won the war; rather it was that the Coalition troops were extremely well trained, well supplied, and professional, versus the rather less trained and professional Iraqi army.

The lesson here is that the Somalis considered the Battle of Mogadishu a VICTORY because the US retreated, despite losing somewhere between 500-1000 dead, and 3000-4000 wounded, while the US forces lost 19 killed and 73 wounded. That sort of mentality takes a different set of tools and a different mindset to fight.

That’s really the military lesson of the second half of the 20th century and the first quarter of the 21st. Fighting insurgencies and irregulars is NOT a fight that a conventional military can really win. The US learned it in Vietnam, Iraq and Afghanistan, the Russians learned in Afghanistan, the Israelis confront it periodically in Gaza, and so on.

How is the Korean War anything other than a UN win? The North tried to conquer the South, it failed, end of story. In a defensive war, survival IS victory.

That’s true, but from what I’ve read of many Chinese Internet posts, it’s considered a Chinese victory and UN defeat because, at a certain point, the opposite was also true - the UN and South Korea tried to conquer all of North Korea, but China flooded in troops and pushed them back to the middle of the peninsula.

There’s enough in the muddled Korean War for everyone to declare victory by their own lens.

1st Phase: North invades South but is foiled by UN; UN victory
2nd Phase: South and UN push deep north but are thrown back by China; UN defeat

Afghanistan War: Those in power have no interest in learning lessons.

Maybe that’s the lesson: not every war needs to be WW2. You don’t HAVE to crush the enemy. Sometimes you can just fight a bit and then negotiate a cease fire or a peace agreement. It’s a lesson the world once knew, and then forgot.

How do you begin to compare a conventional war with defined fronts where you are on one side and the enemy on the other to fighting a gorilla war against people who disappear into the night?

Wasn’t that one of the major problems with the Vietnam War? That the generals were trying to apply lessons learned from conventional wars?

Main advantages in South Korea as I see it:

  • As TokyoBayer states: Korea had a clear, unambiguous conventional-war frontline; and the ceasefire did mean cease fire, with guarantors who were serious that if broken it will mean hot war again.
  • South Korea had no active ongoing internal insurgency.
  • South Korea had no porous land borders through which the internal insurgency could reach sanctuary or resupply, or through which the opponent could easily circumvent the frontline and infiltrate.
  • In Korea you had the advantage over Afghanistan of a unified national/cultural identity, with an organic desire to nation-(re)build, already there during the harsh Japanese colonial rule.
  • The US-backed government in South Korea quickly established power and authority to maintain order and get things done… not as a nice liberal democracy for the first 30-some years, mind you, but it did take on the rebuilding task succesfully.

That’s what happened. I suppose I’m more interested in the why. What was different about South Korea and South Vietnam that the South Koreans were more accepting of American troops?

Can you clarify your question? What do you mean by “more accepting of American troops?”

The factors that @JRDelirious listed are the whys to the success (or lack of failure) of American troops. Are you looking for the reason for these factors?

A major lesson that can be taken from multiple modern wars* is: don’t get stuck propping up an unwilling and/or incompetent ally.

Examples include Austria-Hungary in WWI (German military officers complained “We are fettered to a corpse”), Italy in WWII, Chiang Kai-Shek’s Nationalist Chinese in WWII, South Vietnam, Afghanistan…

*but isn’t.