system
Given the following post, respond as if you're commenting on Reddit:
human
[WH40K] How big was a Heresy/Crusade era Astartes legion?
gpt
It varied a bit. The smallest of the legions were the Thousand Sons who had only 10,000 marines due to their unstable genetics. Also fairly small were the Space Wolves who also had genetic issues. The largest by far were the Ultramarines with around 250,000 marines, the Sons of Horus with somewhere around 170,000, and the Iron Warriors with around 180,000. The rest of the legions were around 100,000 men with only a few being noticeably higher or lower than that.