Q:
Seize of Borderlands/Eternal Battlegrounds
That’ s a top-secret of ANet and also a parameter that they tuned a bit from time to time.
Approximately 100 per map and side, EB maybe a bit more than BLs.
Ceterum censeo SFR esse delendam!
From what was gathered/estimated (since Anet refuse to give a straight answer all the time), it’s 80 on BLs per side, and 100 on EB… except it seems it’s more a total for every side on a map, and you can get a side with more than that and sides capped at less than that (due to the fact you get the outnumered buff with numbers of players that aren’t compatible with a 80/100 player cap on said side).