There was a program on the history channel a number of months back that dealt with exactly that, at least in Europe. IIRC, terrorism and insurgency did occur after the fall of Berlin by a number of factions, both Nazi-sympathetic and others (say, groups drawn to the power vacuum); Japan, I don’t know.
But in both cases, I think the insurgency failed to continue (or even form) because everyone was sick of fighting: the Allies had won, and we knew it, and that was that; the Axis was defeated, and they knew it, and that was that. No one wanted to fight any more.
In modern times, it may very well be that overwhelming, lightning-fast victory - the hallmark of modern warfare - doesn’t sufficiently plant and grow the idea of defeat into the minds of the other side. I’m sure there’s more to it, but it’s worth a thought.
I think your getting at something important here… and added to the fact that it was overwhelmingly an american force… and the perception of an invasion was complete.
That’s certainly very true – the home turf advantage is very useful – but it’s not the only factor. When guerilla tactics have been adapted for offensive warfare, they’ve been a very effective tool of conquest.
In the Thirteenth Century, Chinggis Khan (aka Genghis Khan) built what was arguably the largest land empire in the world (depending on your defintion of empire). Starting from what is today Mongolia, he conquered what’s now China, Korea, India, Russia, and the Middle East.
For the point of view of the people they conquered, the Mongols were primitive. The only technological innovation they had was the stirrup, which allowed them to fire a bow while mounted. They had no metal armour, no swords, no shields. They should have – from the technology-obsessed point of view – lost.
What the Mongols had was speed, strategy, and flexibility. When they went into battle against armoured European knights, the knights (weighed down by their armour) moved in slowly on horseback, while the Mongols fired volley after volley of arrows. If the knights got too close, the Mongols would quickly fall back, and fire a little more.
Metal armour was a double-edged sword – it offered some protection, but if it was ever broken, you have a bit of jagged metal in your wound. The Mongols wore silk cloth for armour. Sounds silly, but if an arrow ever pierced their skin, the silk would bend in around the arrowhead, creating a protection against in infection. The Mongols also invented the use of horns and flags to give new orders in the heat of battle. This meant they could change strategy and formation quickly. The knights had to relay commands by word of mouth.
(Might sound like I’m making an argument for technology here, but I’m not – Europeans had horns and flags, and they could buy silk. The Mongols just came up with a new way to use these things)
Finally, the Mongols did not need a supply line. If necessary, they could forage, and famously drank the blood of their horses if they had no other options. No supply lines means no weak point to exploit.
All this is just to point out that all the technology and numbers in the world won’t save you if your opponents are faster and more creative than you are, and if they can adapt to changing conditions more easily. In war, the little guy wins with surprising frequency.
This may explain why the most powerful military in human history keeps reaching stalemates with peoples with outdated weaponry, homemade bombs, and caves and underground trenches for bases.
Simple: they surrendered because they were ordered to surrender. The same qualities that made them such unquestioning fighting machines also made them lay down their arms.
Plus, according to Barbara Tuchman, the Germans have a fierce aversion to guerilla warfare in any form. The Prussian mentality that dominated their military just couldn’t wrap their minds around it - that’s why they were wiping out resisting towns before the Nazis.