I see this little confusion has flared up again, in the Sanction Race no less.
The name Invicta, which is Latin for "undefeated", doesn't mean "never lost." It's the OOC motto of Kent, which is the home of one of our founders.
If it really meant what you think it means, we'd have had to give it up the first time an Invicta member lost a ground battle. Which I lost one of, I think, in the SOLID war last year.
Wikipedia has a lot more information on our name. I will note that a conditional surrender is mentioned there, right in the freaking article.
Which, like it or not, is what Invicta got. We were offered a white peace, turned it down, twice, the second time we were approached we made a counteroffer which we expected to be refused, and it was accepted. That's what happened.
You can ask Näktergal. She figured it out.