Mosby 's Rangers became infamous among Union soldiers due to their frequent raids on supply trains and couriers .
In January 1863 , John S. Mosby was given command of the 43rd Battalion , Partisan Rangers , a fast - striking cavalry unit .
43rd Battalion     became infamous among Union soldiers due to 43rd Battalion 's frequent raids on supply trains and couriers .
In January 1863 , John S. Mosby was given command of the 43rd Battalion , Partisan Rangers , a fast - striking cavalry unit .