To test if adding more enemies races could help in getting more enemies coming to siege in DF 40.x i decided to quickly make 3 more, based on the goblin templates .
I generated a smaller region for 50 years, then started a fortress mode game, and made sure when choosing my location that every possible enemies were listed (so i wouldn't embark in a location in which none can reach).
I even noticed that i had 2 towers listed , so in the middle of goblins, hobgoblins, orcs and duergar ( they're D&D evil versions of dwarves ) , i had 2 source of undead enemies.
All was going well at first, i had decided to build a surface fortress instead of a classic underground one and had some fun with it so far, and with all the time spent in making rooftop for every building i didn't noticed how much time was going on and just completely forgot about making walls or any kind of defense.
A year moved with only a couple of kobold thieves popping up and 2 small waves of migrant from time to time, winter came, a year without invader, but in the same time i was just building up my village , not yet mass producing goods and wealth so no real surprise.
When suddenly
Damn, i checked and noticed it was 5 undead, while 5 units sounds ridiculous in comparison to what you were attacked with in 34.11 , undead are massively stronger than in 34.11
So 5 undeads were far enough to destroy my whole populations that i quickly drafted into military.
I then moved my guys in stations, waiting for them to just panick in terror and run away because running away in terror is the only thing dwarves can do in the 1st year of no-discipline training/exploit , but they didn't to my surprise.
I checked where the undead were and understood why my military wasn't running away in terror and my village was still standing : the enemy "army" had disappeared.
Oh well, looks like small and nearly never happening invasions aren't the only 40.x problems ...