My favorite mod of all time is The Battlegrounds 1 and 2 for Half Life Deathmatch and Deathmatch: Source, respectively. It's about the American Revolution, and allows you to play as a British regular or an American volunteer in several large multiplayer maps. Each side has three character classes.
The weapons are flintlock muskets and rifles, swords, knives, and bayonets. Reloading is slow (they are breach-loaders, after all), something like 7 seconds, so when the action gets close and your weapon is discharged, you resort to the bayonet.
The game has a great community and is still being tweaked and added to. Look for the player Rooster Cogburn. Check it out: www.bgmod.com