u/CommercialLiving2217

I've been trying to figure this out fully since release. I think it is a common knowledge among us EU5 players that the slave workforce mechanic is at best buggy and at its worst is broken and useless, but, trying to make it work to recruit elite slave army regiments (Janissary, Mamluk) is just straight up frustrating!

After doing some research and read some online posts about this subject (not a lot of players mentioning this, they probably all just gave up), I come up with what I believe is the best setup to successfully fully staff the barracks:

1. Since I'm playing as Ottoman, I did not accept greek as a culture so all of my locations in western anatolia, constantinople area and Edirne are all only integrated, not cored.
2. I place 4 Janissary Barracks in 4 of my cities with the most greek populations: Constantinople, Edirne, Izmit and Smyrna
3. I also place 1 slave market, subsidized, in each of those cities. I deleted all other slave market within the same market area to try and funnel incoming influx of slaves into only those 4 cities.
4. I set building priority to "Infrastructure first, then most profitable" to ensure that my barrack will be filled first.
5. Every last day of the month I check the trade screen to make sure there's no slave export trade (I have trade automated)

Results:

After a little over a year I managed to fully staffed and maintain employment on 3 of the barracks: Edirne, Constantinople and Izmit. They are all fully staffed at 2000/2000 and never lose employment. The last barrack in Smyrna get staffed up to 1835/2000 and then it stopped. It did not go down or up it is basically frozen at that number as if it hits a hard cap. I don't know is causing it because Smyrna has around 70% greek population, just like Edirne. It has 25% control, just like in Edirne and yet the game couldn't or wouldn't fully staff the barrack there.

The only difference Smyrna has compared to the other 3 cities is that it is an overwhelmingly sunni majority, over 90%. As I understand though the game allows enslavement of same religion pops so this should be a non-issue.

What I have tried to fix it:

1. I deleted the slave markets in constantinople, edirne and izmit to try and funnel everything into smyrna. It did not work
2. After I deleted the other slave markets I went to war with the byzantine and captured several thousand slaves. None of them went to smyrna and to staff the barrack. NONE. It's still stuck at 1835
3. I manually created 2 slave import trades one from Tbilisi and one from Caffa. Since there's only one slave market in constantinople market all the slaves that are coming in should go to Smyrna and yet again it failed to fully staff the barrack

Important note:

I did mention that Smyrna is overwhelmingly sunni as a matter of fact the only other religion in smyrna is orthodox. How many people in smyrna are orthodox? 1835

Conclusion:

If you play the ottoman and are planning to field a sizeable number of janissary regiments, to be able to do so you 100% can not make greek an accepted culture. This will make the campaign significantly more challenging because you have to go through the first century, at east, with most of your realm at relatively low control.

The best set up from my experience is 1 slave market and 1 barrack. Adding another level to the slave market did not seem to make the barrack staffing goes faster and without a slave market in the same city the barrack will not be filled at all.

Although it is only one case but I truly believe that somehow religion is also a factor in this. There's no other explanation to the Smyrna anomaly other than you can't enslave people from the same religion.

In my other ottoman save my biggest frustration was that the barracks would get randomly depopulated for no apparent reason. I suspect that it has something to do with having slave markets in other location within the same market node. It has not happen in this save yet and I let the game run for a whole year through war and everything and I manage to get the barrack fully staffed and running.

Importing slaves through trade did not seem to help with quickly staffing the barracks or I just could not figure it out. Capturing slaves through war does work although I don't know why it did not work with the barrack in Smyrna. Also if you have trade automated make sure you check every couple of months or so and delete every trade export you find. This can deplete your slave pops very quickly.

I don't know what happen with Smyrna and why the barrack there stalled. I'm hoping someone here might be able to come up with an explanation. Please reply and share me your experience and/or frustration trying to figure out this system.