Checking Morale for Smaller Units
Another point I seem to have overlooked in the 1870 rules involved circumstances of morale checks. Single stand units are proportionally penalized in the rules for losses i.e., they're docked 3 from their morale grade for each combat point lost)... but there's nothing in the rules that states when single stand units must check their morale! A single battalion/stand could lose 2/3 of its strength (and notionally be down by 6 morale points), but would never have to check its morale, since none of the morale checking criteria applied (except maybe "losses to artillery fire").
So, the fix for that (which has been incorporated into the 1859/64 and 1866 rules) is this: Two and three-stand units check at each stand loss, and single stands check at each point loss. The exception to this is if these small units are the survivors or portions of once-whole regiments, as noted in the rules. They would continue to check as regiments, since the remnants of the rest of the unit is "implied".
A: Since a flank attack is mentioned as being outside the defender's frontal 90 degree arc (in the section describing cavalry charges), a rear attack is hereby defined as being within the defender's rear 90 degrees. This also applies to infantry charges.