In military contexts, a train is the logistical transport elements accompanying a military force. Often called a supply train or baggage train, it has the job of providing materiel for their associated combat forces when in the field. For sieges, the additional siege engines or artillery, ammunition, and its required transport was called a siege train. These military terms predate, and do not imply a railway train, though railways are often employed for modern logistics, and can include armored trains.
Historically for land forces, this usually referred to forces employing wagons, horses, mules, oxen, camels, or even elephants. These can still be useful where difficult weather or topography limit use of railways, trucks, sealift, or airlift.
The United States Department of Defense Dictionary of Military and Associated Terms defined the term "train" as:
A service force or group of service elements that provides logistic support, e.g., an organization of naval auxiliary ships or merchant ships or merchant ships attached to a fleet for this purpose; similarly, the vehicles and operating personnel that furnish supply, evacuation, and maintenance services to a land unit.