The sentence in question is as follows (the part that I have a question about is in bold):
The context goes something like this: the Fighting Gymnastics Club, led by Club President Emi, attacks Reiko, a member of the Comics Appreciation Club. They fully expected to beat the tar out of her, but she beats the tar out of them instead. Now it is just Reiko and Emi facing each other in a showdown.
Here are some more sentences to add to the context:
“Reiko, you aren’t just CA, are you!?”
It was a strange story from the start (but…). She was under orders to attack Onizuka, Reiko who is in the same class with her when she was coming home from school. **それも体操部全員でかかれとは、**no matter how low on the fighting ranks her own club was, it did not make sense. The reason is that their opponents are the unappealing culture clubs and the lowly Comics Appreciation Club at that!
Okay, I’m going to try to break down that part of the sentence into pieces.
それも: It seems that it is often translated as “and that” or “at that”.
体操部全員: I am pretty sure it is translated as “all the Gymnastics Club members”.
でかかれ: Okay, this one was tricky for me. Why? Because as Kotobank かかる shows, the term has a long list of definitions. Well, not as long as the lists of definitions of some words in English, but I digress. In spite of that, I think it is translated as “attack with” or “swoop down on her with”.
とは: This term has me stumped. Kotobank とは does have a list of definitions, but the hard part is figuring out which definition I should go with. I am pretty sure that this term is not defining the preceding phrase. I also don’t think it expresses strong emotions (or does it?). Right now, I think it might be an emphasizer for “と”.
I think that the sentence fragment is translated as “And saying to swoop down on her with all the Gymnastics Club members at that,…”
Am I on the right track with this? I would really appreciate your help with this.