Both articles refered to by Kosyanenko above support what I have indictaed, and as most of us agree, that it is in fact MORAL effect that will determine the outcome. That problem being that effect is obtained by such a large number of factors, all with varying degrees and dependant on the often unique situation at that moment, that it is almost impossible to accurately replicate in a simulation.
If it was such a mathmatically quantifiable process (as all games ultimately are) then wars would not be fought!! They would be calculated and the outcome pre-determined!!
Both articles above again use examples of the unusual to discredit or explain away the norm. Ultimately it was the victor's determination and aggressiveness that prevailed and the factors that achieved their moral accendancy over the vanquished were again unique and many.
To do an effective simulation requires a vast amount of factors and their varying degrees in relation to the situation to be available to the calculation. There is a huge array of situations the calculations must be tested on. Add to these calculations the varying quality of troops training and leadership, mental and physical conditions, national and 'regimental' values and you see that .......this is a big ask....yet to be better achieved commercially than the current HPS titles!
Get some backroom, academic, historian, techo who's experience of fear is loosing his job or his internet connection, has never been in a physical fight, let alone put his life on the line by standing toe to toe with an equally determined and brutal opponant hell bent on your pain and distruction

doing the calculations

. Then the likelyhood of the values of all those factors being justifiable and the simulation being 'realistic' is not going to happen.
This is not a dig at the current HPS teams I might hasten to add!!However, food for thought. A surprise flank attack with a couple of devestating vollys did do it for L'Guard (middle guard only!) and the British did run at Albuera from a surprise Lancers flank charge! The value of surprise and support, flank and rear threats, I feel is way underestimated in current HPS titles. I do like Bills idea of multiple inf melees as well

In fact I would make them possible up to a normal inf move (terrain dictated) and Cav melee moves likewise one move(terrain dictated)

Include with this a variable (logical paramaters) and random (again with a logical scale) Charge/Melee Determination Role/Factor for both the attacker and defender and you begin to achieve the random and unpredicatbility (to a justifiable level) that will allow/achieve the odd Thann example, as above.
Now if someone wants to pay me what I'm earning now to sit for months (maybe years?) reading, calculating, testing and re-testing such a sytem I would relish and jump at the opportunity

I believe it is more and more achievable as computers become more capable of such calculations.
ONWARD