Attack rearmost - how does it really work?

[analytic_kernel]

I don't know how the algorithm works, but pg. 74 of the manual makes it sound like ZOC could be a consideration. The edge of one formation passing by another one may get tangled in its zone of control, and perhaps that almost entirely tangles the formations. I've seen battlefield behavior that could be explained this way.

It could also be attack rearmost troops of nearest enemy formation rather than rearmost formation. I've seen behavior which looks like that as well....

Just speculation - not an algorithm or any sort of methodical knowledge - but might be stuff to look for during experimentation.