trying to understand why my horse is so aggressive with other horses not from her herd

Question
QUESTION: Hi, I have a 5 year old thoroughbred mare who is sweet, respectful, and loves humans, and her two buddies being her mother and an older arabian mare. When she was a couple weeks old, i brought in the arab to stay with them, to form a kind of herd. Dancer, her mother, would get after the arab to stay away, and my filly would apparently get a big kick out of it and chase after the arab, rearing and kicking. when it came to weaning time, at about 6 months, i kicked mom out to the pasture, which shares a fenceline where i kept my filly and the arab. So mom and filly could nuzzle and weaning wouldn't be as traumatic. After mom was out, the arab would get after my filly, teaching her herd dynamics i'm sure. And here's when I made a mistake. My filly followed the arab into the stall to be with her, and the arab was kicking like crazy in the stall to get filly away, so I put the arab back out to pasture with mom. So, filly was by herself in paddock and could see and touch other horses but was separated. I did ground work with her in the meantime, she was probably separated for a year and a half. Time came for breaking, and thinking she was stronger now to take blows from the arab, i had then acclimated her back into the little herd. She immediately goes to her mother for protection, and at about 2 years old her mother lets her walk all over her (not blaming mama horse, thought maybe this was interesting) anyway, mama horse develops food allergy to pasture, so she comes in to permanently live in paddock instead. Arab and filly out in pasture, arab boss, seems like filly is understanding herd dynamics, ect. Here's where I don't understand, anytime she is around other horses (not arab or mom) she is extremely aggressive, ears pinned, squealing, rearing, striking, kicking, bucking, tail swishing. every horse we come across, regardless of how hard i try and get her attention- waving arms (when i'm on the ground haha), yelling, jerking her face, smacking her rear. It actually makes it worse, she gets more mad and gets more aggressive with the horse, it's like I don't exist. Whatever I did wrong, oh man am I paying for it. She is 5 now, and she still acts like this with other horses even though we've ridden with the same 5 horses the past 3 years. Also, when we went on a trailride with 2 of the horses we ride with, she could be sandwiched between the two and didn't care. I was rubbing knees on both sides! I'm sure it was a safety with numbers kind of thing, she always has to be the lead horse on a trailride, and when she gets unsure, she lets the other horses come up beside her for confidence then goes back out to the front. She is definetly not "buddy" or "barn" sour, and is very independent. She works well under saddle with a few protests on what we should be doing, but I get my point across and we continue working. She comes to me neighing and running in the pasture, seeming always happy to see me, I sometimes give treats, mostly scratches and rubs. I have a wonderful bond with her mother. I have put her out with my riding buddie's horses, and she aggressively attacked (at 2 years old!) the lead horse and got pushed away from the herd rightly so, this happened with two different herds, one of which she stayed with for 2-3 weeks, and never was let into the herd. Am I unconsciously promoting this behavior or is this a respect issue on my part? Or was separating her so young with a memory of being "attacked" by the arab so traumatic for her she thinks to protect herself from any new horse? Or maybe she's trying to make a herd with any horse and be dominant? It's probably a mix of all those things I suppose. She loves any human. I have tried correcting her behavior and redirecting her attention before it happens by working in tight circles (correction, which seems to work most of the time, but oh man do I get dizzy when there's a 5 horses going around) or moving her away from a horse closing in. But moving away seemed to just put off the problem. Please help me understand what the heck I could be doing wrong, and what I could work on. Need to be a better horsewoman! Thank you for your time!

ANSWER: Well the horse has told you every time that you don't know what you are doing. So now I can going to tell you, put the horse out with others horses, leave and stop thinking you need to save and protect and watch and get involved.

All horses bite and kick and push and fight and have new herd issues, of course humans think they know better and always try and help and fix and save and end up screwing it up.

Put the horse out with a herd, leave it out for a week and stay of it. YOU are the problem not the horse.

I answer this about 30 times in my videos and on my site.


---------- FOLLOW-UP ----------

QUESTION: Thank you, just making sure if I needed to do something else on top of keeping her in a different herd. I appreciate it!

Answer
I just posted a video where I say horses are the best teachers of horses. They will work it out and all horses either lead or follow, when two horses meet they are never equal, one will higher and one lower. What you see as aggression, horse see as a way of life.