Could someone describe stronghold battles to me?

_1204_, on Oct 24 2018 - 10:36, said: I tried the wiki... but that just confused me more.    I've been considering maybe trying out a clan. The issue is I only have tier 6s (and that's all I really want). I remember back a long time ago I was in a clan, and we could do a mode where we fought other clans (like 6v6) in tier 6s. I was happy I could use my su100 for something finally. I'm pretty sure it was stronghold battles, but I'm not entirely sure. This was well over a year ago...   Are stronghold battles tier 6? And is there anything else besides randoms that I can play my hellcat and kv2?