Judging by the equipment and construction around the area, it can be assumed that Riley's Charge was a fortification left abandoned from the Indian Wars, the Mexican-American War, or some other notable conflict, as cannons and cannonballs litter the area.
The Black on Red Red Dead Redemption Logo T-Shirt Avatar Award is unlocked by opening a chest found inside the burnt down cabin here.
This is the only place in the entirety of Red Dead Redepmtion where cannons are found mounted on wheels.
When in or around the Rathskeller Fork or the ArmadilloSaloon, a man named Lewis Shelton (who is the brother of Ira Shelton) intends to visit Riley's Charge, stating that their grandfather died at the location; presumably he was a soldier who was killed in the battle which took place there.
There is a lone tent and campsite on the winding road above the cabin which provides an excellent place to observe the surrounding area. This campsite may have served as an observation post or spotters post to direct the cannon-fire onto the enemy or watch for approaching enemy forces during the battle that this location is named for. Just further along the same ridge is a money chest containing around $15-25.
This could be a reference to Pickett's charge at Gettysburg, for the defenders were dug in and there was a charge by the opposing army, just as it seems this is.
It is possible to find the Legendary Jackalope in this area.
When visiting this area at night, wolves spawn constantly. This is a good way to gather lots of hides without the use of bait, as the more wolves you kill, the more will be attracted to the area.
Judging from the artillery lying around, it is likely this is a reference to John O'Reilly who captained the Saint Patrick's battalion after they deserted the United States Army during the Mexican-American War and took up arms against them.