Mass Battle Stats - scaling things up

In most RPGs, the combat stats for an individual might just as well be the stats for a unit. Here are some thoughts on effective scaling:

The main thing is to choose an appropriate scale. Generally speaking, you want a 2-digit number of figures/chits on the board for it to feel like a battle, and something like 20-50 figures is ideal.

Times Ten Scale - "Battlesystem"
A unit is 10 men - a squad. A group of units is a company of ca 100 men.
Distances on the board/battlemat are x3, feet become yards, so 5' > 15' or 5 yards.
Time is also x3, so each unit round is 3 rounds of individual combat. Resolve 3 individual rounds for your PCs, then roll a unit round to see how the army is doing.

Times One Hundred Scale - "Hastings"
A unit is 100 men - a company or century. A group of units is a brigade of ca 1,000 men.
Distances on the board/battlemat are x10, so 5' > 50'.
Time is also x10, so each unit round is 10 rounds of individual combat. Resolve 10 individual rounds for your PCs, then roll a unit round to see how the army is doing.

Few battles will need a larger scale, but...

Times One Thousand Scale - "Cannae"
A unit is 1000 men - a brigade. A group of units is an army of ca 10,000 men.
Distances on the board/battlemat are x30, so 5' > 50 yards, 150'.
Time is also x30, so each unit round is 30 rounds of individual combat. Resolve up to 30 individual rounds for your PCs, then roll a unit round to see how the army is doing.

Examples:
A force of 200 men becomes 20 units, in 10-man squads.
A force of 2,000 men becomes 20 units, in 100 man companies.
A force of 20,000 men becomes 20 units, in 1000 man brigades.

Resolution
Treat each figure as a unit of the appropriate scale. Roll initiative etc as normal. One roll per side is fine, but individual rolls by organised group of units (company/brigade/army) or their leaders works well too, and may better reflect the disorganised state of battle.
Have groups of figures/units organised into cohorts/brigades of ca 10 act on their turns.
For a unit group, roll to hit for all units/figures. Use average weapon damage. Add up the number of hits and multiply by damage. Remove figures whose hp equal up to that damage total. Fractions can be ignored, since some damage is bound to be wasted, except for lone units.
Use morale rules as normal for your game.