Ahh.  I must say this is my favorite sortie.  There is nothing like seeing a bear vs a stag.  Both realms are fairly well matched and there is usually no telling who might win.  This battle takes place in the Albion sector of Hadrians Wall.  Why there?  Simple really, convience.  Even though Emain is a very good place to RvR it is very hazardous for Hibernians of any level to get there.  For low levels its usually tantamount to suicide unless accompied by someone with a very good speed buff.  From either frontier fortress each realm can warp to Albion and be at the front in a few minutes.  Here is a map indicating the areas of combat.