For millenia, horses carried the armies of the world. Other pack animals, along with horses, carried the heavy loads of food, ammunition, and equipment but horses predominated as the mounts for cavalry and the draft power for heavy artillery and supply wagons. But that all changed during a very short time in the early twentieth century. Rapid mechanization, starting in World War I, transformed armies by substituting machine power for animal power. Horses that numbered in the millions (worldwide) were replaced by millions of trucks, tractors, jeeps, motorcycles and eventually helicopters plus light and heavy planes.
Soldier of a Cavalry machine gun platoon crossing an obstacle with his pack horse during a field problem at Ft. Riley, KS, April 1942.
Today in WW II: 1 Aug 1943 Ploesti Raid: 178 B-24 Liberator bombers flew over 1200 miles from a base in North Africa to Ploesti, Romania for a daring, low level attack on oil production facilities. More↓
Mountain troops in training with pack mules, 1942.
American history has an almost continuous presence of cavalry. Gen. George Washington created mounted cavalry units in 1776, during the Revolutionary War, some of which were in continuous existence through the War of 1812. After a gap in organized cavalry units from 1815 to 1833, new cavalry units were established that are the direct lineal ancestors of modern units. Cavalry as an arm of the U.S. Army was firmly established by the Civil War and, in the Indian Wars of the westward expansion, became symbolic of the role, function, and power of the U.S. Army.
In the first half of the 20th century, horses and mules, once the mainstay of military transportation, all but disappeared from those roles. The internal combustion engine that emerged in the early 1900s quickly found its way into military equipment and operations. In World War I, trucks greatly reduced the former dependence on horses while tractors were introduced as artillery prime movers and the tank appeared for the first time. Between World Wars I and II, a debate raged over the proper role of armored vehicles for cavalry and infantry support as well as the suitability of motor transportation for supply and artillery under varying conditions. Infantry was augmented by tanks but, for a few decades, horse cavalry continued. By the late 1930s, as World War II loomed, the Cavalry became partially mechanized, expanding that mechanization and joining with tanks to form the Armored Force for World War II. Reconnaissance was transformed by jeeps and motorcycles, as well as aircraft, another role lost by the horse. Except for a few battle zones of exceptionally rugged conditions, legions of pack animals were almost completely replaced by the hundreds of thousands of trucks produced during WW II.
U.S. Army animals being loaded onto a cargo plane for transport over the Himalayan Mountains to Nationalist Chinese forces, Sahmaw airstrip, India, February 1945.
This transition happened earliest most rapidly in the United States, but other nations quickly followed, often using equipment developed or manufactured in the U.S. By the last year of World War II, the U.S. Army was almost totally mechanized, its allies largely so, while the Germans and Japanese remained dependent on horses for artillery and logistics. After the defeat of the Axis powers in 1945, the world's armies converted almost completely to motorized prime movers, self-propelled artillery and armor, and cargo trucks and troop transporters, as well as versatile jeeps and light vehicles for reconnaissance, command, and weapons platforms.
After much controversy, in 1950 the U.S. Army mechanized cavalry and armored units were finally welded together into a single Armor branch. Another transition followed, to airmobile units, completing the transformation from animal power to full mechanization in three dimensions.
The mounted arm first had the horse, next the armored car or tank, and then the helicopter as its means of mobility. By the late 20th century the only roles left for horses and mules were ceremonial.
A few die-hard Cavalry officers insisted on maintaining a minimal capability to train and manage animals, in case of war in very unfavorable terrain, like Italy or CBI in WW II. This faith was actually rewarded in Afghanistan in 2001-2002 where Special Forces found that the only option for movement in parts of that harsh and rugged land was by horse or mule. Understanding that pack animals have their unique uses, even in a time of computers, lasers, GPS and the stealth bomber, the Dept. of Defense authorized the Marine Corps Mountain Warfare Training Center to create a rigorous Animal Packers Course for all the services and the Army Special Forces issued a field manual on the subject.
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