Yes, its an awful rule that makes you conduct 'soak-off attacks'. If you are adjacent to an enemy unit, it has to be attacked (within certain restrictions). So if you have, for example, two enemy units next to each other, and your main attack is adjacent to both, then both must be attacked. So, you do a crap poor odds attack against one unit, and a concentrated attack against the other. I seem to remember it was a common rule that was used in other AH games from that period.
“O Lord God, let me not be disgraced in my old days.”
'We few, we happy few, we band of brothers'