Sudden aggressive hen with babies

[Angeladhmh]

So I have a hen named Meadow who had chicks several weeks ago and has never ever been aggressive. Well today she has been attacking my other adult hen Easter quite often what could be the reason?? She lets me pet her and hold her. She is only aggressive to Easter

 

[Finchbreeder]

She "for reasons unknown" probably sees the other hen as a threat to her chicks.
Sometimes new mums get neurotic.