Conquered planet rebel over and over again

[mianmar]

I have a big juicy planet target of 17B population, but as soon as I conquer the planet population rebels and captures the planet back to defender.
I repeat the process so many times I don't have the will to continue playing the game.

the manual says you should leave planet with no army on it, because then population won't rebel, I try that too and it doesn't work.

I noticed the unhappiness is -32, most of it causes due to "recently conquered" modifier, and also the system has one more enemy planet which adds to unhappiness.

I tried to capture the other planet first (which is much smaller btw. 500M population) but it rebels too.

I was unable to defeat the enemy, and instead forced him to subjugation, now the other AI declared war on this same target and he is also unable to capture these planets, lol.

Any suggestions? [8D]

[Retreat1970]

More troops. Sounds simple but that's it. 3:1 or 4:1 attack/defend just so there's enough left over to hold it until tensions calm.

[Aeson]

As Retreat1970 suggested, if you want to keep the colony with its population more or less intact, you'll need to leave an army in place until things calm down. If you can get an orbital base with recreational and medical facilities built over the planet, that'll help, though at -32 happiness I'd still expect to see rebellions for a time after getting such facilities into operation. Ensuring that there are nearby mining bases supplying at least a few luxury resources and basic strategic resources may also help.

If you don't mind a spot of genocide, or at least involuntary resettlement, you can also take measures to reduce the colony's population, thereby reducing the size of the garrison necessary to suppress future rebellions. Beware: such activities tend to have detrimental effects on your relations with foreign powers and can lead to unrest on previously loyal worlds within your own empire.

[Shogouki]

Massive armies will do the trick. I never leave a conquered world without an absolutely massive garrison, especially if they're a race that instinctively dislikes my race.

[Bingeling]

Since the happiness modifier is mentioned, it is probably not an issue, but if on manual taxes, make sure to check tax settings for the newly conquered one.

Personally I can't really remember having much issues with this, but there are some species that are very sensitive about "war with own species" and such things. And I probably do not leave contested colonies around for longer than necessary (invade both at once, but both will not fall at the same time).

[mianmar]

Thank you guys for help. [&o]

Planet invaded with 3,6K vs 1,4K troops.
rebels failed to regain colony back, and in the meantime happiness dropped to -2 which is just fine for now hehe.

[Shogouki]

Yeah the happiness will take some time to even out, especially if they instinctively dislike you. If you can try building a fortified bunker there so if anymore uprisings happen your troops will have a major defensive bonus.

[Uncle Lumpy]

On the plus side, putting down rebellions is a quick way for your ground troops to gain experience before you attempt to conquer another empire. I often leave only a few troops on a recently conquered colony in the hopes they will rebel. I leave enough to put the rebellion down, and if I'm lucky, the colony will rebel two or three times. Each time it does, my troops there gain additional experience. One of the main Wonders I try and build is the Troop Cloning facility. With that facility you can create some very powerful invasion forces that are relatively small in number (less maintenance costs). If you're not one of the more militant species, it's really great if one of the first independents you conquer is one (Mortalen, Naxxillian, or one of the bugs). You can incorporate them into your invasion force. Not only do they start out as more powerful per unit, but their maintenance cost is usually much lower. For even easier experience gain, I really like it when there's a pirate base on the newly conquered colony, too. I only leave a large occupying force on conquered colony if I'm at war with that colony's Empire. Then I'm not after experience, I'm after gaining and holding territory.