It has been done 10,000 times before in the past, it will be done 10,000 times in the future. I wouldn't class it as an exploit, the yo-yo bug is a definite bug wherein an army that can retreat into a fort doesn't because there is an adjacent unit blocking its way :/ It is as I said; a low blow and I apologise for using it, but I must overcome the odds that are against me by any legal means.
Just let it be a lesson to ye to not leave free units lying around, especially near garrisoned cities/forts where they can retreat into.











