Mare being bullied, what can I do?

[TheOldTrout]

My mare's just beginning to have some turn out after a period of box rest (she was lame). Yesterday I just put her out for a bit while I did her stable, haynets and water. While I was doing this, another livery told me I might want to trot mare up when I got her in as another one had been chasing her round and round at a gallop.
Went to get mare in. The other mare repeatedly attacked her when she got close to the gate, not just a running at her with ears back to get her away from the gate but a full on chase round and round, biting at her quarters when she got within reach (my rug now has a large tear in it) and not giving up. My mare was scared to go to the gate in the end. She came in with heat in her foreleg and a torn rug, neither of which she went out with.
What's best to do? I'm keeping her in for now but that's not a long term solution - and she loves her field, when she's not being bullied. Will bullymare behave better when there's more grass and her hormones have calmed down, if she's in season?

 

[Pearlsasinger]

When a horse has been out of the herd for a protracted period of time, such as box rest, it is good practice to reintroduce them gradually. I would expect the YO to put up an electric fence to section off a bit of the field or allow your horse to go into a neighbouring field until the herd has settled back down again.

 

[TheOldTrout]

Thanks Pearl. YO isn't interested in changing field arrangements (I did say what had happened to my mare).
That's interesting about the herd dynamics - Thursday was the first time my mare had had any trouble since I started turning her back out and it was bullymare's first day turned out after some time in having lost a shoe. Maybe bullymare was trying to reassert her position in the herd. (When I was trying to bring mine in, bullymare was attacking another one in the field when she couldn't reach mine.)
At least mine doesn't seem to have suffered any damage in the attack.

 

[Chianti]

If there enough grass to keep them interested? If not can you put some hay out? I would be very worried about this. Your yard owner sounds horrible. My pony was out quite happily with another smaller pony. A bigger pony was put in with them - all was well for a few weeks but then one day the new pony started chasing mine. He got him in a corner a couple of times. Eventually mine ran through the fence into the next door field-he looked petrified. My YO took the new pony out of the field when I said how worried I was. If you have to put yours back out then I would email or text the YO so she knows how concerned you are. Heaven forbid something happened to your mare you then have evidence that you raised a concern.

 

[TheOldTrout]

Bullymare has injured herself so is staying in and mine has been going out with no problems. I had a better conversation with YO, who thinks the mares' behaviour will calm down once the spring grass comes through (you were right about that, Chianti!) and that in the meantime I can put my mare in a paddock instead of the field if I'm worried. So it's all looking a lot more positive than it was a week ago