Cavalry (or horsemen) were soldiers or warriors who fought mounted on horseback. Cavalry were historically the third oldest (after infantry and chariotry) and the most mobile of the combat arms.
The designation of cavalry was not usually given to any military force that used other animals, such as camels or mules. Infantry who moved on horseback, but dismounted to fight on foot, were known in the 17th and early 18th centuries as dragoons, a class of mounted infantry which later evolved into cavalry proper while retaining their historic title.
A man fighting from horseback also had the advantages of greater height, speed, and inertial mass over an opponent on foot. Another element of horse mounted warfare is the psychological impact a mounted soldier can inflict on an opponent.
The mobility and shock value of the cavalry was greatly appreciated and exploited in armed forces in the Ancient and Middle Ages; some forces were mostly cavalry, particularly in nomadic societies of Asia, notably the Mongol armies. In Europe cavalry became increasingly armored (heavy), and eventually became known for the mounted knights. During the 17th century cavalry in Europe lost most of its armor, ineffective against the muskets and cannon which were coming into use, and by the mid-19th century armor had mainly fallen into disuse, with some regiments retained a small thickened cuirass that offered protection against lances and sabres and some protection against shot.
In battle Cavalry had a great advantage over the common foot soldier. The speed, mobility, height and force of impact allowed by the horse allowed the horseman a great advantage over a soldier on foot. Mounted troops carrying projectile weapons also had the ability to harass enemy armies. This tactic has been used since ancient times. Horses are also capable of trampling enemies knocked down during battle; with some cavalry charges acting as stampedes.
Another universal use of cavalry since ancient times was their role as scouts and reconnaissance groups. The speed and mobility of light cavalry made them ideal scouts and even civilizations that did not use a comparatively notable amount of cavalry, like the Romans or the Chinese, used them as scouts.
The Huns, Scythians, Parthians (also known as Arsacid), Carthaginians, Celts, all renowned horsemen of the ancient world, used this to great affect against powerful enemies like Rome.
The first recorded use of war horses (excluding Chariots) and horseback riding was from the Scythians: existing from 800 BC. They shared similarities to the future Hunnic and Mongolian Empires; using recurved bows while on horseback to launch successful raids against Empires while remaining nomadic on the Eurasian Steppe.
Throughout history cavalry has been an integral part of most nomadic cultures, especially the aggressive civilizations that raided and pillaged other civilizations to acquire resources. People like the Mongols, Huns, Russian Cossacks, Indian Marathas, Arab Bedouins, some Native American people such as the Comanche, Sioux, Lakota etc became well known horsemen since use of cavalry greatly complemented their lifestyle.
When speaking of heavy cavalry, warriors using spears or swords could rush enemy foot soldiers and quickly crush disorganized enemy units, Alexander the Great used this tactic to great affect in his conquest, using an "Hammer and Anvil" approach. The medieval knights were mounted "shock troopers" of their time, they crushed through enemy flanks using heavy weapons (mostly melee weapons) while protected by their heavy armor.
In the ancient world and Middle Ages, the speed and mobility of light cavalry allowed the use of various effective combat tactics. Mounted archers were ideal for "hit and run" tactics, a tactic commonly used by Native American warriors from the colonial age to the early 20th century. This tactic was also used by Indian horsemen, specially the Marathas.
Mounted archers used the speed and maneuverability of their horses to use the "parthian shot" tactics which involved shooting arrows or a gun at an enemy while pretending to retreat or run away from them. As the enemy is in pursuit, they would be constantly hit by arrows while being unable to use their melee weapons until they got close enough. First developed by Parthians, this tactic was used by Huns, Mongols, Seljuk Turks and Native Americans as their light horsemen had accurate archery skills and were faster than most other horsemen at their times. The Saracens also used this tactic against heavily armored European knights during the Crusades.
Use of parthian shot eventually leads to the "feigned retreat" tactic. This involved using a small force to agitate the entire enemy army and then retreating, keeping them focused on trying to pursue the attackers by constantly launching hit-and-run attacks and denying them the opportunity for a battle and ultimately luring the disorganized, tired and blindly determined enemy away from their fortified positions and into an ambush by the larger portion of the force. According to the Mongol Expert Timothy May, Ph.D - "the Mongols are all about the feigned retreat". Even after the end of the Mongol reign, former Mongol occupied lands such as Persia or Eastern Europe used good amount of cavalry in their armies.
Cavalry played a key role during the colonial period, specially during the colonization of the Americas. Many natives were not familiar with cavalry and didn't know how to counter them. Small European forces easily managed to take down thousands of native warriors using their cavalry.
Spanish colonization north of Mexico was sparsely populated, but still had Vaquero farms scattered throughout Spanish California and Texas. This lead to several horses on these farms escaping into the wild and thriving as an invasive species known as the Mustangs. Several Native American tribes, especially in the Great Plains, would domesticate these mustangs. The Comanche were founded thanks to their use of cavalry to separate from their parent tribe the Shoshone.
After the widespread adoption of gunpowder, armor started to lose it's merit on battlefields, specially European battlefields. Then the melee cavalry mostly became lightly armored hussars, who carried light weapons (such as the cavalry sabre) and were used to mount surprise attacks and quick flanking attacks on the enemy. This tactic became surprisingly useful when properly utilized in co ordination with battlefield conditions - for example, a surprising cavalry charge using the cover of a fog could change the course of a battle. This tactic was efficiently used by Napoleon. Cavalry raids were also used to cut off enemy supplies.
Mounted dragoons (mounted soldier armed with a musket or blunderbuss) were another addition to European cavalry during this time. The carried lighter weapons compared to standard musketeers, but combined the mobility of horses with the range and power of their firearms.
The largest cavalry charge in history is cited to be the Battle of Vienna on the 12th of September 1683. This battle ended the Siege of Vienna that began July 14th of the same year. Leopold I, Holy Roman Emperor escaped Vienna before the siege to form a Holy League consisting of one of the Ottomans' greatest enemies: The Polish–Lithuanian Commonwealth. The Polish cavalry was led by John III Sobieski: who had many battles against the Ottomans before Vienna. John's experience combined with his elite units led the charge on the Ottoman's west flank. The Ottomans failed to organize their forces fast enough to made a defensive line, and thus the Poles devastated the Ottomans. The Ottomans were forced to retreat and eventually lost Hungary and Balkan territories to the Christian armies; leading to the beginning of the decline of the Ottoman Empire.
Use of cavalry in direct combat started to slowly decline after widespread adoption of early modern firearms like the repeating rifle as use of infantry became more efficient cost-wise. Then the cavalry were primarily used as scouts and reconnaissance groups. Melee cavalry like the hussars and lancers slowly got disbanded. US cavalry served as scouts, raiders and as mounted infantry throughout the American Civil War and the Indian Wars. Armies also started using horses for fast transportation of infantry units while outside battlefield. However bandit like Jesse James and/or guerrilla groups like the Villistas (Mexican revolutionaries lead by Pancho Villa), Native Americans like the Comanche, and Sioux used horses to make lightning raids. It is known that later armies also used cavalry charges while being assisted by rapid firing weapons such as the Gatling gun in tactics like the "suppress and slaughter" tactic. But while such tactics were fast and had high shock value, they had a high chance of turning out to be suicidal at times.
Cavalry also found new success with European superpowers in Imperial operations (irregular warfare), where modern weapons were lacking and the slow moving infantry-artillery train or fixed fortifications were often ineffective against native insurgents. The British Indian Army maintained about forty regiments of cavalry, officered by British and manned by Indian sowars (cavalrymen). Some modern Indian and Pakistani Army regiments can track back their lineage to these famous regiments. The French Army maintained substantial cavalry forces in Algeria and Morocco from 1830 until the Second World War.
After World War 1; cavalry units became inefficient to use in normal warfare. This was thanks to the arrival of weapons with a high rate of fire (like the Vickers Machine Gun), modern artillery, uneven terrain of shellholes, trenches and barbed-wire. In total; 8 million horses died in WWI. Horses in the later months of the war were usually kept as a scouting role when against enemies with machine guns; knowing their new disadvantage to modern weapons. As countries became more and more modern, cavalry was eventually replaced with vehicles.
The largest traditional cavalry battle in history was the Battle of Komarów of the Polish-Soviet War. The famous elite Polish cavalry managed to surround and defeat the larger Soviet force: primarily because miscommunication between the Soviet armies caused the Soviet 1st Cavalry Army to approach Warsaw without any Soviet divisions protecting their flanks.
The Polish Army was still known for their cavalry by the time WWII began in 1939. Contrary to rumors created by Nazi propaganda: the Polish would never intentionally charge at tanks and would instead dismount their horses if they had to maintain their front line. This infamous myth was from the Charge at Krojanty on September 1, 1939: where Polish cavalry commander Kazimierz Mastalerz charged into vulnerable Nazi soldiers. The charge was initially successful, but the Poles were unaware that the Nazis had armored vehicles nearby that managed to easily counter the horsemen. Other armies of WWII (including the Nazis) did use horses; but avoided cavalry charges and used horses primarily for transportation.
The 44th Mongolian Cavalry led the last ancient-style Calvary charge in WWII on 17th November 1941 at The Battle at Yakhroma, with the Axis forces facing no casualties and the Calvary division mostly destroyed (only 30 of the 2,000 horsemen survived).
Amedeo Guillet led the last successful Cavalry attacks against a British army. Amedeo was an Italian officer in the Italian Guerrilla War in Ethiopia (27 November 1941 – October 1943) who used the speed of his horsemen to surprise and confuse British units. This includes multiple successful raids against British infantry that was supported by tanks. Some of his horsemen still used the cavalry saber, and many used pistols or grenades at close range. Cavalry would be used successfully within the initial invasions of Operation Barbarossa: using the speed of the horses to surprise the unprepared Soviet military. The Charge of the Savoia Cavalleria at Izbushensky (24 August 1942) was one of the last successful largescale Cavalry charges in history.
Today; horses are still used for scouts or for traveling across rough terrain that would be too rough for regular vehicles. Cavalry divisions technically do exist in several nations, but are minuscule in size compared to other military wings.
Knights categorized their horses as; All Rounder (basic riding), Palfrey (high class) & Destrier (war horse). All three breeds can be used in battle; but the Destrier was the primary horse for Knights due to this breed's strong muscles. 
Napoleon Bonaparte recognized 3 categories of Cavalry; light, line or medium, and heavy.
Light Cavalry had small riders and small horses. They were designed for scouting and hit-and-run harassment. They were the primary force used to hunt down retreating enemies. They would normally have a curved saber.
Line Cavalry primarily protected the flanks.
Heavy Cavalry would the elite forces. Some kept Curiasses; however the term 'heavy' referred to the weight of the large horse. They were designed to crush enemy lines. It was common for Napoleonic Heavy Cavalry to use straight long sabers.
Most Cavalry units had pistols, but did not rely on it primarily.
Dragoons (Cavalry using small Blunderbusses) were used by multiple weights, but were considered a unique unit among the Cavalry.
The advantages of Cavalry are clear. The horse allowed for a mounted warrior to quickly move around the battle field, hit fast and hard.
The large size of a horse made some melee weapons ineffective against them, and horses are strong enough to trample humans. Their size is also useful when crossing rivers, when Hannibal first entered Italy, his horseman were able to attack an Roman army crossing a river and because the horseman were elevated above the river, they stayed dry and avoid fighting the current.
Despite the advantages of horsemen there were a number of draw back to cavalry.
One of the biggest issues was the use of spears and pikes in an organized fashion. The Greek phalanxes is one such example of this, because of the multiple rows of spear horsemen and there mounts would impale themselves in a frontal charge, so attacking the flanks and rear was preferable.
Additionally horses can be scared fairly easily by unknown animals such as elephants or camels due to their "odd" appearance and smell. The Mongols and Turks faced this problem against elephants during their early invasions of India, the European armies faced similar problem when they faced camels of the Saracens during the Crusades. However horses that are trained around these animals would not panic, making it easier for the camel or elephant using army to use their own cavalry.
Horses also avoided animal corpses and could be scared by the smell of blood. In the 911 AD Siege of Chartres: the Viking Rollo prevented the Franks from attacking with their cavalry by slaughtering the livestock on his boats and using them as a bloody wall to intimidate the Frankish horses.
Loud noises could also startle horses. The noise from a Chariot's wheels is capable of scaring enemy horses unfamiliar with Chariot combat: as seen with Roman cavalry fleeing from Gaulic Charioteers in the 295 BC Battle of Sentinum. Polish Winged Hussars wore wooden wings that would make clacking sounds, scaring enemy horses. Polish horses were not intimidated by the noise since they were trained to ignore it.
Another key disadvantage of cavalry was it's high upkeep and maintenance cost. So some empires that needed to field a vast army over a densely populated land preferred infantry (specially gunpowder armed infantry) over cavalry. Specially the Chinese, Ottoman, Mughal empire faced this problem.
Aztecs and Incas initially were overwhelmed by the exotic Spanish horses; but they made several attempts to counter the cavalry. The Aztec Maquahuitl was claimed to be an effective weapon against horses; although Deadliest Warrior debunked the claim that the weapon could decapitate a horse in one slice. Manco Inca's revolt (1535-1544) had the stone/bronze age Inca make several strategies and tactics to fight Spanish cavalry despite their inferior technology and resources.
- Horsemen can still be knocked off of their horse if hit by a heavy weapon.
- Horses struggled to travel on destroyed roads or up steep Andes hillsides. Narrow city streets were also used for ambushes, as horses struggled to move if their unit was compacted on thin streets.
- Horses can be easily killed by rockslides and boulders, if lured into the traps.
- Large bolas can trip and immobilize horses.
The Cheval de Frise was a cheap yet effective defensive structure designed to defend against Cavalry charges. Believed to have originated in the Medieval Age: it is a series of long spikes anchored into the ground and pointed upwards at a 45 degree angle. The most common design is having the spikes overlap each other in an X shape. The spikes are double sided so that the structure can still function normally even if it somehow is knocked over or upside-down. The bottom spikes are intended to dig into the ground to better absorb the impact of a cavalry charge. Because of the height of a horse, it is expected for the horse to get itself impaled when attempting to charge into or jump over the device. Barbed-Wire effectively replaced the Cheval de Frise as it was cheaper, more portable, could stop infantry as well, and is resistant to artillery bombardments; as the wire would get more entangled instead of being destroyed. Cheval de Frise was still used alongside Barbed Wire. Metallic variations of the Cheval de Frise (including the Czech Hedgehog) can also be used for anti-vehicle and anti-tank defenses.
In the show the first warrior to be seen on Horseback was the Knight, however this was only in the final fight and was likely not a tested factor. The first official use of proper cavalry, was in Alexander the Great vs. Attila the Hun. After this episode Mongol vs Comanche featured mounted horse warriors as well. In the third season features the most mounted warriors to date, however it mostly the commander who is seem on horse back while his soldiers fight on foot.
- There is little to no evidence to suggest that a 'wedge' or 'diamond' formation was used by any Cavalry unit in history; this appears to be a modern myth. However some historians claim that this formation originated with Alexander the Great with his Companion Cavalry.
- Incans called horses 'giant llamas' and Aztecs called them 'weird deer'.
- Llamas can pull 20%-30% of their own weight while horses can pull 15%-25%. However horses are 3 times heavier than llamas; and thus over twice a strong. This is why Llamas cannot be used as Calvary.
- Camels and Elephants were also effective cavalry; although horses were faster and easier to mass breed.
- Zebras are difficult to domesticate due to their hostile nature; which is why Zebra Horsemen didn't exist.
- Rollo the Walker was a Viking that was infamous for his massive size. He was too tall to wide a horse, making him 'The Walker'.
- Saddles are not necessary to ride on a horse; Numidian cavalry frequently rode into battle bareback.
- The Tahki Horse is considered to be the last species of truly feral horses in the world.
- In 2018: Mongolia was estimated to have 13x more horses than the Mongolian human population.
- Napoleon Bonaparte declared that the Cossacks were the greatest light cavalry of his time.