Only works in casual games, didnt try it out in a quick game yet
ok, for this you need baharain, some city nearby and a transport between baharain and the arabian coast.
then you make 10 inf in your city (lets say its the arabian capital) then you move them into your trans and move the trans into baharain. in baharain you make 1 more inf and then move the 11 inf into some city you want to attack:
then you go to lobby and this appears:
i tried moving the second stack that appeared around a little bit, but it seems like the second stack just dissapears next turn:
i attacked different cities in pic one and two, thats not the bug