While it is hard to put precise dates on the decolonization process, those dates chosen represent two of the most significant decolonization successes. Sparking the retreat from empire was Britain’s fulfilled promise of independence for India in 1947. At the other extreme, Rhodesia’s first majority elections spelled doom for the apartheid system.
Time: Early War
Removed after event: No
Decolonization is the best recurring USSR event in the game. In the Early War, it gives the USSR access to two key regions that the USSR otherwise has difficulty getting into. In the Mid War, it becomes one of the few (and strong) “add 4 influence” events. The fact that it comes out much earlier than its US counterpart (Colonial Rear Guards) means that first, the USSR can get to and control countries in those regions before the US, and second, on average, it will be played more often.
Where should I Decolonize into?
As much as possible, you want to Decolonize into Africa rather than Southeast Asia. There are several reasons for this: chief among them is that Africa has multiple open battlegrounds, whereas Southeast Asia only has one. Of course, Asia will be scored before Africa is, and Southeast Asia will be scored on top of that, but Decolonization into Asia is primarily to jumpstart your access. Sooner or later, you will get into Southeast Asia via some combination of crawling east from Iran and Vietnam Revolts. Africa, on the other hand, can be very difficult to fight back in without Decolonization’s help. It is much easier to defend those countries than to flip them, and the US has a head start in access via South Africa.
Turn 1 considerations
On Turn 1, you must be mindful of DEFCON’s effect on Decolonization. Decolonizing into Thailand at DEFCON 4 is a mistake, because the US will just coup you right out, and worst case scenario you’ve just handed the whole region to them. Likewise, Decolonizing into the African battlegrounds at DEFCON 3 is just handing the US a coup target.
Ideally, you will play Decolonization at DEFCON 2 and with the US having no access to Thailand. You can then take your choice of Decolonizing directly into Thailand, or Decolonizing into Malaysia and then grabbing Indonesia as well. If the US is already in Malaysia by the time you trigger Decolonization at DEFCON 2, then you can only place 1 into Thailand and bank on using the China Card to try to take it back if the US only places 3 influence into Thailand.
If you are going to Decolonize into Southeast Asia at DEFCON 4, the US usually won’t be in Malaysia yet. In that case, I like to drop one into Malaysia, which is more difficult to coup out, and in a best-case scenario can seal the US off from access to Thailand altogether. I am not worried about my Africa Decolonization influence, because if he coups me there I can just coup him back.
Turn 2 / 3 considerations
DEFCON should no longer be a concern here, as it is probably at 2. How Decolonization plays out will depend on how much progress you two have made into Southeast Asia:
If neither side has much influence: then rejoice and take the region by dropping one or two Decolonization influence in there.
If you dominate it: you probably don’t need any Decolonization influence there, but 1 into Indonesia is a nice 1VP for Southeast Asia scoring.
If the US dominates it: You should still drop one into Thailand so that you can meaningfully contest the region, and maybe another into Laos/Cambodia to stop the US spread into Asia. But unless you’re headlining Decolonization, this is unlikely to flip Thailand to your side, since the US can probably just repair 1 or 2 influence worth of damage in Thailand. The point is to establish some access so you can do things like threaten use of the China Card or Vietnam Revolts.
Specific African countries
In Africa, Angola is the most critical country to play into, if the US hasn’t already. It gives you both Zaire and Angola, and opens up possibilities for a Botswana play into an easy Africa domination or a South Africa realignment, eliminating all US presence in Africa. Algeria is next in importance, if you have not yet established access to France, because it provides a back-door into the country. (This is an example of Decolonization’s power: when you play into both Thailand and Algeria, you are often forcing the US to confront multiple threats at once, and there is no way they can defend all of them simultaneously.) Nigeria is third (though sometimes more important than Algeria if France is already settled), because it is a country that is otherwise inaccessible without going through an easily-couped non-battleground.
You can think of Africa as being divided into three subregions, divided by non-battlegrounds: Algeria, Angola/Zaire/South Africa, and Nigeria. You want access to all three of them, and although De Gaulle does give you access to Algeria, the only way to get into all of them is with Decolonization.
Early War summary
In the Early War, I will normally drop only one into Southeast Asia, because I will eventually have access to the region anyway and it will merely jumpstart my progress there. Depending on DEFCON and the US position I will place it in Malaysia, Thailand, or sometimes Burma. The remainder of the influence will go into Angola, Algeria, and Nigeria.
Decolonization is such a valuable card that I rarely headline it in the Early War if I am at all concerned about Defectors. Losing it to Defectors is so costly that I would rather be safe and play it on an Action Round unless I knew that Defectors isn’t being headlined (because it’s already been played, because I have it in my hand, or via some psychological read of your opponent, if you are confident in such things).
Past the Early War
In the Mid War, Decolonization remains a top-tier card because it evolves into a “drop 4 influence in Africa” event. By this time, Southeast Asia is likely sewn up, and the fact that it can put 4 influence into a region with mostly 1-stability battlegrounds is still game-changingly powerful.
Along with De-Stalinization, this is a card so powerful you can’t even send it to space until after the Turn 3 reshuffle. If I’m not able to hold it to Turn 3, I will absolutely send it to space, or hold it until I can. It is of such importance that I would rather trigger Blockade and lose West Germany before triggering Decolonization: at least then, the USSR has to invest 4 Ops to get the 2VP swing.* Decolonization will mean much more than that, come Africa Scoring (or sometimes Asia Scoring).
In the Mid War, Decolonization is still very bad, since it is only a 2 Ops card and you need 4 Ops to repair its damage. It can be one of those AR7 plays (to mitigate its effect), but more commonly it is just an auto-space.
Its existence is why I try to get into Angola and then Zaire as quickly as I can. USSR control of Angola cuts you off from two battlegrounds and puts you at a severe disadvantage in Africa.
* Of course it can be more than 2VP, depending on whether it hands over Domination VPs or possibly Europe Control. If you must lose West Germany, then as the Blockade article notes, you should do so on the last AR.