The Mongol military tactics and organization enabled the Mongol Empire to conquer nearly all of continental Asia, the Middle East and parts of eastern Europe.
The original foundation of that system was an extension of the nomadic lifestyle of the Mongols. Other elements were invented by Genghis Khan, his generals, and his successors. Technologies useful to attack fortifications were adapted from other cultures, and foreign technical experts integrated into the command structures.
For the larger part of the 13th century, the Mongols lost only a few battles using that system, and always returned to turn the result around in their favor. In many cases, they won against significantly larger opposing armies. Their first defeat in the West came in 1223 at the Battle of Samara Bend by the hands of the Volga Bulgars. The second one was at the Battle of Ain Jalut in 1260, against the first army, which was specifically trained to use their own tactics against them. But again they would return over 40 years later and defeat the Egyptian Mamluks at the Battle of Wadi al-Khazandar in 1299 and annex Syria, Palestine as well as Gaza. The Mongols suffered defeats in attempted invasions of Vietnam India and Japan. But while the empire became divided around the same time, its combined size and influence remained largely intact for more than another hundred years.
In accordance with Mongol civil and social structure, outstanding obedience and firm discipline provided the backbone for their military. According to Italian explorer Giovanni da Pian del Caprine, "The Tatars—that is, the Mongols—are the most obedient people in the world in regard to their leaders, more so even than our own clergy to their superiors. They hold them in the greatest reverence and never tell them a lie". Army delegates were chosen either by their blood association of the Khan family or by military-related meritocracy. Each delegate received responsibility and their respective titles:
Transfers between units were forbidden. The leaders on each level had significant license to execute their orders in the way they considered best. This command structure proved to be highly flexible and allowed the Mongol army to attack en masse, divide into somewhat smaller groups to encircle and lead enemies into an ambush, or divide into small groups of 10 to mop up a fleeing and broken army. Individual soldiers were responsible for their equipment, weapons, and up to five mounts, although they fought as part of a unit. Their families and herds would accompany them on foreign expeditions.