Book series about a group of humans rediscovered by an interstellar empire

Question

I read it when I was young. A group of humans in one system are separated from a powerful human empire for several hundred years. The large empire accidentally finds them and slowly tries to conquer them over a period of books. The defenders are outnumbered and have small ships, but they have some sort of gate technology which allows them to move ships and torpedoes where the empire ships are not expecting them.

The Empire is described as overconfident. Eventually I remember they send a massive fleet and we follow its progress for some time.

I remember them as human, but they could be something else. Also, I believe, but am not sure, that the small group had some contact with an alien/religious species/order within their own system. They turned to them for advice/alliance as the books moved on.

Lastly, the gates were the huge point of much of the story. They allowed the weaker group to win time and again.

Answer 1

This sounds very much like "The Regiment" series by John Dalmas.

It includes the teleportation "gates" (which it turns out only mentally prepared people can use, I.E. stable personalities due to the philosophy of the Tyss). The invaders are lead by a central computer (as far as I can remember). The religious aspect is the philosophy of the people from the planet Tyss.

I mostly remember this from one of the following books, "The White Regiment", which follows the first group(s) of "non-Tyss" being trained as that type of warrior.