Those tactics I've seen in history books on ancient battles. I love the slant formation or as you call it the echelon. I usually put elite units on the leading edge for maximum impact. It's really good agaisnt the computer since it seems prepared for you to attack in a straight line. You should also say that as you make contact with the enemy, gradually bring all of the other units into line.

Also, the charge through the middle with the cav move might work, but I tried it before and my cav panicked a bit.