You could do worse than BBB night interval rules. In each phase, scenario attacker moves first.
Withdraw to cover or out of small-arms range.
Other infantry/cavalry units may move up to 12" where no enemy is closer to them than a friendly unit.
Formation changes.
Redeploy guns up to 12", staying beyond 12" of enemy (this is 2/3 artillery with smoothbores).
Generals move anywhere.
resupply ammo.
Rally/recovery.