We've used that system (Janx', above) in our campaign. Found it worked well if the overall party size is small, and the number of "named characters" is low, but we were trying to 'break apart' units each time a PC or named NPC interacts with them. We had a lot of named characters, which meant it degenerated into a ton of individual-on-individual interactions, and bogged down horribly.
I'd recommend taking his advice from that second-to-last paragraph: "
You should not have individiuals fighting "Units" Break those units into individuals. " 
The system works well for abstracting the 'the orc King attacks a band of ten first level fighters (8 hp x 10 = 80). He gets three attacks, and hits twice for 24 points of damage. The first-level fighters are down to 56 hit points. Move on. There's no need to break them up.
If you break a unit up for the PC's benefit, creating individual-on-individual interactions, try to keep the number of areas where that is happening limited, or 'break them up' only for determining how many attack rolls there are, rather than going as far as giving them individual counters, initiative, etc.
If you have a fumble/critical system, you might drop the fumbles and crits for "units" - it doesn't make sense for a unit of ten to all drop their swords at the same time, or to all score critical hits at the same time; save your fumbles and crits for individual rolls when the PC's are involved.
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There's another option I've used for 'sketching' a battle scene. It doesn't have to be a wargame if the PC's aren't in command.  
 
Instead of feeling like you have to map out the entirety of the battle, you might map out only what the PC's are actively aware of. A large-scale engagement kicks up a lot of dust, and if you go wander around Gettysburg or other historical battle sites, it becomes clear that it is impossible to see everything which was going on from any vantage point.
If the PC's aren't in command or likely to ascend to command during the battle, you can use any system you like to resolve the "off camera" aspects of the battle, and map out only the parts which individual PC's can see. 
I've used "scripted outcome", "Opposed d20 rolls (one for each 'front' or 'flank'), with modifiers for morale, numbers, and ground," and "Based on extrapolating how the PC's encounter is going" to resolve off-camera aspects of a larger battle, each with good effect. I very much recommend those approaches as much more convenient for the DM if it makes sense for your campaign world.