American Expeditionary Forces is a Red Dead Redemption posse.
About the posse
In an effort to extend federal control over the new western territories and reign in the extreme lawlessness therein, President William Howard Taft, 27th President of the United States, activated the 3rd and 10th Mounted Rifles and reorganized them into frontier expeditionary forces.
The United States Armed Forces is actively recruiting young men to defend the frontier territories. If you would like to join, please visit the AEF recruiting station nearest you.