Top 10 Greatest Armies in History

In recorded history, countless successful armies came from the time of mighty Sumerians (4th millennium BC) until the current sole superpower of the World (United States).
Criteria (for being one of the greatest armies) should be established based on an achievements and achievements can be determined in the form of (1) Conquest (How much lands they occupied from the inhabitant part of the region of the earth), (2) Victories (Most importantly decisive victories/victories which were turning point in history worth counted), (3) Durability of their success rate (It can be judged in the form of a timeline), (4) victories against Superpower Empires worth counted (It is a bonus point if they conquered/submitted them successfully), (5) level of influence in conquered societies/territories (6) what type of level of odds they overcame e.g. like tough terrain, harsh weather environment and well-resourced, outnumbered, robust enemies. 
Any army is going to be scrutinized under these patterns with their level of degree.  
     

10) Hunnic Army:

Hunnic hordes roamed across western and eastern Europe from the 4^th to 5^th centuries and caused great havoc. They relied on their high mobility and a shrewd sense of when to attack and when to withdraw. They often created loud noises during the war to amplify the psychological element of fear into the hearts of their enemies. They contain excellent horsemanship and their archers' fire arrows even if they were back of their horse with great speed. However, they were not entirely good at pitched battles. Christopher Kelly claims that Attila sought to avoid losses “as far as possible, large scale engagements with the Roman army”. An important part of their strategy was to pretend their opponent that they were retreating and then turning back and attacked the disordered enemy units. They have preferred to defeat their enemies by deceit, surprise attack, and cutting off their supplies. Especially under Attila the Hun (known as Scourge of God), Hunnic hordes devastated most of Europe and taken tens of thousands of lives. However, their hordes were not entirely powerful enough to conquer the capitals of both the eastern and western Roman Empire. Their conquest was short-lived with barren results. 

9) Macedonian army:

The army of Macedon was among the greatest military forces of the ancient world. It was created under the guidance of King Philip II and made them formidable in the face of the earth. Later on, his son Alexander the Great led his invincible phalanxes to conquer each state from the Adriatic Sea to Indus River. Macedonian heavy infantry primarily consists of foot champions, Hypaspists, and Greek hoplites, and light infantry consists of Peltasts and Cretan archers. Companion cavalry (heavy cavalry unit) considered to be one of the finest cavalries in the ancient world. However, the short-lived Macedonian Empire left a lasting legacy of its army and Alexander’s military tactics and strategy still teach in military academies across the globe.  

8) Soviet/Red Army:

Soviet army (1917-1991 AD) was one of the most dominant forces on a global theater during and after World War 2. During the War, the Red Army won a decisive victory over the Germans at Stalingrad (which was the turning point in the history of World War 2), overran entire Eastern Europe, captured Berlin (at the Battle of Berlin) and ending the Nazi Germany. In addition to it, Soviet ground forces (together with his ally North Vietnam) able to defeat US-led South Vietnam during the Vietnam War (1955-1975) and converted entire Vietnam into a friendly communist regime. 

7) Russian Imperial/Czar Army:

For 180 years (1721-1900), the Russian Empire was considered as the world’s superpower because of its rapid advancement and modernization of its army, which eventually able them to conquer entire Northern Asia (Siberia), Central Asia and almost entire Eastern Europe. People’s Militia (Irregular Troops), Hussar, Ulan, and Imperial Guard are among the prominent features of the Imperial Russian Army. Russian army (1721-1917 AD) plays a decisive role in defeating and conquering the First French Empire of Napoleon Bonaparte. Alexander Suvorov was considered among the most famous commander of the imperial army and also one of the greatest military commanders of all time.

6) American/United States Army:

American army (1775-Present) was established during the revolutionary wars of independence from the British and gradually start to grow by absorbing the native Red Indian population and Spanish territories in west America. During the Spanish-American War (1898), the US (United States) became a global power after defeating Spanish. The entry of the US army in World War 1 (1917) was instrumental in defeating the German forces and gave victory to Allies. In World War 2, the American army was fighting on both German and Japanese front. US army has only forced on planet earth that successfully conquered the Japanese island while no other foreign nation in the history of Japan able to occupy this remote obscure island. After World War 2, the United States along with the Soviet Union emerged as Superpower of the world; start an armed race and proxy wars against each other to spread their ideologies (Capitalism/Socialism), in which US army prevailed as a result of their successful covert operations in Soviet-Afghan war and USSR (Union of Soviet Socialist Republics) collapsed and the USA left as a sole superpower up to the present day.

5) Ottoman/Turkish Army:

For 230 years (1453-1683 AD), Ottoman Empire was considered a trans-continental hyperpower. Thanks to his elite Janissaries, powerful artillery, canons, firearms, etc, the Ottoman army was truly a gun powder force; their use and adoption of such weapons were so rapid that they surpass both Europeans and middle eastern opponents. In most cases, the Ottoman combination of using both Janissary/firearm units and artillery/canons were proved to be decisive in many battles. Perfect adoption in gun powder weapons and excellent technique of using those weapons endures the legacy of the Ottoman Empire for centuries. 

4) Roman/Byzantine Army:

The Roman army was one of the most durable armed forces in human history; it lasted from 753 BC to 1453 AD. They managed to defeat numerous European, Asian, and African forces, created a well-disciplined and trained military unit. It overwhelmed the Carthaginian forces, hold the barbaric invasions of Huns, successful counter-attacks against Sassanian Persians after losing most of his territory (during Byzantine-Sassanian Wars in 602-628 AD), survive the onslaught of Arabs (by defeating them twice during the siege of Constantinople in 674-678 & 717-718 AD), and his impenetrable walls of Constantinople survived every single attack from the outside world {except the Conquest of Constantinople by Crusaders (1204) and Ottoman Turks (1453)} besides ruled over vast swathes of Europe, Eastern Mediterranean, and Northern Africa for centuries. Augustus (founder of the Roman Empire), created the elite force of formidable legions and alongside Auxilia, a regular troops with a similar number with legions, recruited from the non-citizen inhabitants of the empire. However, the Roman army was evolved with needs; develop a method of tactics and strategy that able to surpass any other force on the planet earth. 

3) Achaemenid/Persian Army:

Achaemenid Persian army was the greatest force of the ancient world. They arose from southwestern Iran under the command of his greatest ancient conqueror and ruler Cyrus the Great, famously known as King of the four corners of the world, a legendary figure describes by Koran & Bible (Old Testament) as Dhul-Qarnayn (Arabic: ذو القرنين‎ - Owner of the Two Horns; symbolizes his two kingdoms i.e. Persis and Media). Persian infantry consists of Immortals, Sparabara, and Takabara. Immortals were among the most fearsome unit of Achaemenids and Sparabara as well (famous for fighting with enemy hand-to-hand single combat) and also Takabara one of the tough ones. Persians heavily relied on archery (Composite Bow). Most importantly their armored heavy cavalry units and chariots were the deadliest ones. As per the Herodotus “The armored Persian horsemen and their death-dealing chariots were invincible. No man dared to face them". With 120,000 soldiers (according to Xenophon), the Persian Achaemenid army ruled more than 2/3 of the entire known earth and controlled 1/3 of the entire world's population.

2) Mongol/Tartar Army:

For two centuries (1206-1405 AD), from Mongol Genghis Khan to Tartar Tamerlane (Taimur), Mongol/Tartar army dominated and conquered most of the Eurasian landmass and created the largest empire in human history. Their rapid mobility of mounted horse archers and cavalry was part of his major strength that no other force on the planet earth could wield. Their military achievements were vastly outnumbered by any other nations in terms of conquest. Mongols didn’t much influence the societies/territories which they conquered; instead, they assimilated into their cultures, resulted in losing the durability of their own empire. However, the stupendous fighting force of Mongols made them capable enough to unite all lands from the Pacific Ocean to the Mediterranean Sea. More than half of the Mongol troops primarily composed of light cavalry and horse archers and the rest of the others were heavily armored units. Like Arabian horses, Mongol horses have excellent stamina; able to survive in tough weather conditions with little care and providing excellent mileage. Mongol/Tartar hordes were the most ferocious and fearsome force in entire military history. They appeared from the Mongolian and south Siberian forest steppes and slaughtered 50 million people (from 1206 to 1405 AD) through his conquest. But this is not the only case Tartars did, they also brought up with them a biological weapon that they even not know i.e. Bubonic Plague (Black Death); it spreads from Central Asia to Europe, taken 75 to 200 million lives because Tatars slaughtered the huge population in conquered cities (particularly during the siege of Kaffa in Crimea), facilitated the disease to spread across Europe. If we have taken into account all of their brutality and bloodbath, resulted from their conquest, it surpasses any other nations on the planet earth.

Mongol army invaded the entire Asia (except Arabian Peninsula), Eastern and Central Europe (except The Novgorod Republic ) in which they successfully conquered the entire regions of Mongolia, Central Asia, China, Korea, Iran, Iraq, Afghanistan, Transcaucasia, Southwestern Turkey, Northwestern Pakistan, Southern Siberia and most of the Eastern Europe. However, their invasions failed in South Asia, Southeast Asia, Central Europe, Syria, and Japan despite several incursions.
Tamerlane the Great (Taimur) united the Mongols/Tartars once again, restores all the remnants of former Mongol Empire and created the Tartar (Timurid) Empire which ultimately ruled over half of the known world. But Taimur’s death signifies the end of Mongol’s glory and eventual demise.  

1) Rashidun/Arab Army:

Rise of Islam traces went back to history where Rashidun (Rightly Guided) army (632-661 AD) plays an important role in the early establishment and expansion of the caliphate to its largest extent (from the Atlantic Ocean to the borders of China). The early strategy of Rashidun soldiers was to exploit every single weakness of enemies with minimum losses. Despite low-standard army in terms of military equipment and strength as compared to Sassanian Persians and Byzantine Romans, Rashidun force able to defeat both of these two superpowers and conquered the entire Sassanian Persian Empire and 3 quarters of the entire Byzantine Empire. These all accomplishments came as an outcome of their finest strategies by capable commanders such as Khalid Bin Al-Waleed, Abu Ubaidah Ibn Jarrah, Saad Bin Abi Waqas and Amr Ibn Alas, etc, supreme administration of conquered territories by caliphs, and inspiration/motivation came from the Holy Book (Koran) and teachings of the Islamic prophet Muhammad (صلى الله عليه و سلم). In all of the Rashidun Commanders, Khalid bin Al-Waleed was among the most successful commander, under his command Muslims defeated all Bedouin rivals in Arabia and united them under a single political entity called Caliphate. After that, he and his army defeated the numerically superior forces of Byzantine Empire (379,300 & 100,000 Soldiers, according to American historians Treadgold and Walter Emil Kaegi respectively) and Sassanian Empire (100,000 to 130,000 Soldiers, according to recent archaeological evidence on campaign bases near the Great Wall of Gorgan), eventually paved the way for ultimate conquest. Rashidun army used his greatest advantage as strength against both Persians and Romans i.e. Mobility, which latter both these armies didn’t have. Their army was mostly composed of camel mounted soldiers and with the help of light cavalry, they were able to engage and disengage enemy units at any time and attacks from the flank or rear. Their special unit was called Mubarizun (one who gives offer), famously known as champions, an effective force of infantry which demoralizes any enemy force by killing their champions. The total strength of Rashidun soldiers was very few in numbers from 13,000 to 41,000 during the first Caliph Abu Bakr (632-634 AD), but despite all of these facts, they conquered the entire Arabian Peninsula and further went on to clash with two existing superpowers. In all the wars against Byzantine Romans and Sassanian Persians, the Caliphate Mujaheddin faced outnumbered and well-equipped soldiers of Persians and Romans. At one time, they faced the combined power of both Byzantines and Sassanians (ten times greater than Muslims) at the Battle of Firaz (634).

In history, no one’s army created such influence like Rashidun/Orthodox Caliphate’s army created as a result of their military achievements. They brought up Islam into the entire regions of the Middle East, Northern Africa and parts of Central and South Asia in a manner of just two decades. Later on, all Persian, Turkic, Mongol, and Berber dynasties fell under their influence and adopted Islam (as well as their state religion) and carried the Islamic legacy up to the 20^th century. Rashidun Caliphate was a precursor to the next Arab caliphates such as Omayyad (661-750 AD) and Abbasid (750-1258 AD). This Orthodox Caliphate left lasting footprints on the Islamic World and their Soldiers (Mujaheddin) provides the central role (along with just and wise administration of their Caliphs) for altering the landscapes of the entire earth from Northern Africa to Central Asia.