Hearts of Iron IV

Your goal is to build EU union. Overall it will take about 40 minutes to get this achievement with max speed ingame. Might have to restart your game if civil war does not go the way it should

Follow this tree:

1. Repeal the may constitution
2. Regulate the finance sector (Chose 2nd option) - Triggered german civil war for me and Facist germany has to lose.
3. Economic Resucitation
4. Devalue the schilling
5. Legalize political opposition
6. Hold Elections (Pick Karl Renner)
7. The Danubian Federation
8. Invite The Danubian Countries (but dont invite anyone)
9. Danubian Unity
10. Inviting the observers
11. Danubian Diplomacy
12. Via The danub to Europe (Invite Kingdom of Germany to EU union)

Now you need 500 to Annex germany. Once that is done achievement is yours 😃

There are alot of YT guides aswell about it in different ways if this does not work. But this seemed to be the fastest way i could do it myself.

From the newest DLC this is probably the easiest achievement to get.
You either have to own the DLC yourself of do the subscription to hearts of iron 4 to get all game content.

Dam busting raid can be done against Belgium so play German Reich and play it out normally as you do but before conquering Belgium do the Raids on them.
Raids usually need strategic bomber and tactical bombers.