Assault Gun is a set of free wargame rules for miniature wargaming WWII large-scale battles.
In Assault Gun, one unit is typically either an infantry regiment or a battalion, such as tanks. This means that a large, recognisable action of WWII can be fought in a day with a manageable number of units.
The rules are free to download from the Yahoo! site here. The rules are included in the files section, and are absolutely free to download.
The site also includes several orders of battle covering armies, corps and divisions; and there are (presently) two fully-tested scenarios: Wintergewitter (Manstein's attempted relief of Stalingrad) and Kasserine Pass.