So i didn't actually put much thought into the eagles because they were more of a driving force for moze than anything else. But fuck that it feels bad if i don't have something so here we go

The eagles are based very loosely on old roman style centurions. Hence the latin motto We came, we saw, we conquered. They use the phalanx method of war and all that. They are disciplined and professional on the job but they are mercs so you know their off times tend to get ... .rowdy. Where they differ is they are a purely defence group. Towns would hire them to bolster defenses and train their militia. I envision they only ever have like 300 members with about half being warriors and the rest being Logistics members that help manage supplies, Help craft defenses and shit like that. In a defensive fight the eagles win 9 times out of ten times. But that is their weakness. 

Now as stated in the dagger heart section i left the them (daggerheart) identity blank so John could use them how they pleased and so their reason is also up to john. Maybe the duchess wanted to hire the eagles before the unbound and someone didn't like that. Maybe they were lied too about what they were carrying in their mission and were attacked for it. Maybe it doesn't matter. Whatever the case, like daggerheart identity is not that important it is less about why the eagles were attacked and more about they were. 

And what an attack it was. Daggerheart knew everything about the eagles. And knew that their best bet was to attack the eagles when they were in between jobs for towns. As they were likely to take low risk escort jobs until the next big job happened. And they were right and so they set a trap. They had exploding glyphs to decimate lines and cause confusion and they had mostly long range archery and magic users to pick them off at a distance. That being said in my humble opinion the eagles are badass and they managed to organize quickly and put up a hell of a fight. But unfortunately it was too much and the eagles fell. The only survivors were Moze and her group and about 20 new recruits that usually guarded their camp. They split soon after that.