For the “First Winchester” battle, in which you have to take the town of Winchester, Virginia from a comparably sized Union force, you can use flanking movements or attack the Union defenders head-on. Unsurprisingly, flanking movements tend to work better.
Flanking around the Union left, you place all your units at the far left of the starting box, then move due south in a narrow column along the left edge of the map, until you get south of the town; you then turn east, and finally north to enter the town in a run and use its buildings to defend against counterattacks after taking the flag.
It is easier and quicker, though bloodier, to flank around the Union right: Place all your units at the far right of the starting box, and then at the start run two brigades due south. The rest should curve around to the right edge of the map and then straight down. The two running brigades, and their detached skirmishers, should encounter Union skirmishers almost immediately and keep them occupied while the rest of the force heads down the map towards the northeast corner of the town. Toward the end of the journey the main force will have to fight more Union skirmishers, and after CSA enters the town and takes the flag, Union counterattacks will be extended and fierce. But defending with the town buildings as cover is much easier than attacking, so CSA should win every time—albeit with about 50 percent more casualties, compared to the left-side approach.
The basic strategy I have outlined above also works for this battle when using the J&P Rebalance Mod. However, when using the mod, always check ahead for the numbers of units you can bring to each battle—those numbers may differ from the ones in the vanilla game.