This work briefly highlights the main points of the development of the army in the Middle Ages in Western Europe: changes in the principles of its recruitment, organizational structure, basic principles of tactics and strategy, and social status.
A detailed description of this battle has come to us in the account of Jordan.
Of greatest interest to us is Jordan’s description of the battle formations of the Roman army: Aetius’ army had a center and two wings, and Aetius placed the most experienced and proven troops on the flanks, leaving the weakest allies in the center. Jordanes motivates this decision of Aetius with the concern that these allies would not abandon him during the battle.
Soon after this battle, the Western Roman Empire, unable to withstand military, social and economic cataclysms, collapsed. From this moment, the period of the history of barbarian kingdoms begins in Western Europe, and in the East the history of the Eastern Roman Empire continues, which received the name Byzantium from modern historians.
Western Europe: From the Barbarian Kingdoms to the Carolingian Empire.
In the V-VI centuries. A number of barbarian kingdoms are emerging on the territory of Western Europe: in Italy - the kingdom of the Ostrogoths, ruled by Theodoric, on the Iberian Peninsula - the kingdom of the Visigoths, and in the territory of Roman Gaul - the kingdom of the Franks.
In the military sphere at this time, complete chaos reigned, since three forces were simultaneously present in the same space: on the one hand, the forces of the barbarian kings, who were still poorly organized armed formations, consisting of almost all the free men of the tribe.
On the other hand, there are the remnants of Roman legions led by Roman provincial governors (a classic example of this kind is the Roman contingent in Northern Gaul, led by the governor of this province Syagrius and defeated in 487 by the Franks under the leadership of Clovis).
Finally, on the third side, there were private detachments of secular and church magnates, consisting of armed slaves ( antrustions), or from warriors who received land and gold from the magnate for their service ( buccellaria).
Under these conditions, armies of a new type began to form, which included the three components mentioned above. A classic example of the European army of the 6th-7th centuries. can be considered the army of the Franks.
Initially, the army was composed of all free men of the tribe capable of handling weapons. For their service, they received land allotments from the newly conquered lands from the king. Every year in the spring, the army gathered in the capital of the kingdom for a general military review - “March fields”.
At this meeting, the leader, and then the king, announced new decrees, announced campaigns and their dates, and checked the quality of the weapons of his warriors. The Franks fought on foot, using horses only to get to the battlefield.
Frankish infantry formations “...they copied the shape of the ancient phalanx, gradually increasing the depth of its formation...”. Their armament consisted of short spears, battle axes (Francisca), long double-edged swords (Spata) and skramasaks (short sword with a long handle and a single-edged leaf-shaped blade 6.5 cm wide and 45-80 cm long). Weapons (especially swords) were usually richly decorated, and the appearance of the weapon often testified to the nobility of its owner.
However, in the 8th century. Significant changes were taking place in the structure of the Frankish army, which entailed changes in other armies of Europe.
In 718, the Arabs, who had previously captured the Iberian Peninsula and conquered the kingdom of the Visigoths, crossed the Pyrenees and invaded Gaul.
The actual ruler of the Frankish kingdom at that time, Majordomo Charles Martell, was forced to find ways to stop them.
He was faced with two problems at once: firstly, the land reserves of the royal fiscal were depleted, and there was nowhere else to get land from to reward soldiers, and secondly, as several battles showed, the Frankish infantry was unable to effectively resist the Arab cavalry.
To solve them, he carried out the secularization of church lands, thus receiving a sufficient land fund to reward his soldiers, and announced that from now on, not the militia of all free Franks was going to war, but only people who were able to purchase a full set of cavalry weapons: a war horse , spear, shield, sword and armor, which included leggings, armor and a helmet.
The composition of the dry rations of European armies now resembles the menu of a good restaurant. In the Middle Ages, a fighter’s diet was much more brutal.
“Evil War” is what winter campaigns were called in the Middle Ages. The army was critically dependent on weather and food supplies. If the enemy captured a food train, the soldiers were doomed in enemy territory. Therefore, large campaigns began after the harvest, but before heavy rains - otherwise the carts and siege engines would get stuck in the mud.
“An army marches while its stomach is full” - Napoleon Bonaparte.
French engraving from the Hundred Years' War (1337–1453). Source: Wikipedia
During World War II, the daily allowance of Red Army soldiers should have included 800 g of rye bread (from October to March - 900 g), 500 g of potatoes, 320 g of other vegetables, 170 g of cereals and pasta, 150 g of meat, 100 g of fish, 30 g shortening or lard, 20 g vegetable oil, 35 g sugar. Total according to documents - 3450 calories. At the forefront, the diet could change significantly.
Wartime ration
For a soldier on a campaign to be able to remove and hang packs on a horse, push a cart, swing an ax, carry stakes and pitch tents, he needed up to 5,000 calories. No food - no army. Therefore, if the campaign progressed successfully, the soldiers ate better than most medieval classes.
Today, 3,000 calories is considered the norm for a man with an active lifestyle.
Each day, everyone was allocated up to 1 kilogram of good bread and 400 grams of salted or smoked meat. A supply of “live canned goods”—several dozen heads of cattle—was slaughtered in a critical situation or to boost morale before an important battle. In this case, they ate everything, right down to the entrails and tails, from which they made porridge and soups. Constant consumption of crackers causes diarrhea, so the dried bread was thrown there, into a common cauldron.
Pepper, saffron, dried fruits and honey were given to the sick and wounded. The rest seasoned their food with onions, garlic, vinegar, and less often with mustard. In northern Europe, fighters were also given lard or ghee, and in the south - olive oil. There was almost always cheese on the table.
The medieval soldier's diet was supplemented with salted herring or cod, and dried river fish. All this was washed down with beer or cheap wine.
Medieval military train with provisions and equipment. Illustration from the book "Hausbuch" of 1480. Source: Wikipedia
drunken sea
In the galleys, even slaves and convicts ate better than commoners on land. The rowers were fed bean soup, bean stew, and breadcrumbs. About 100 grams of meat and cheese were given out per day. In the late Middle Ages, the standard of meat increased and lard appeared in the diet. Those at the oars had the most nutritious food - this is how the sailors were motivated to fight for this place.
Food on ships was generously served with wine - from 1 liter per day for officers, 0.5 for sailors. At a signal from the squadron admiral, all rowers could be given a bonus glass for good work. Beer supplemented the calorie requirement. In total, the sailor drank a liter or two of alcohol per day. It is not surprising that fights and riots were frequent.
So to speak, the “infantry renaissance” in the military affairs of medieval Europe began with the appearance of the Swiss infantry in the battle arena. For European military practice, the Swiss used completely new infantry tactics, or rather, well-forgotten old ones - ancient ones. Its appearance was the result of two centuries of combat experience of the Swiss cantons, accumulated in the wars with the Germans. Only with the formation of the state union of “forest lands” (Schwyz, Uri and Unteralden) in 1291 with a single government and command, the famous Swiss “battle” could take shape.
The mountainous terrain did not allow the creation of strong cavalry, but the line infantry in combination with riflemen was brilliantly organized. It is not known who was the author of this system, but undoubtedly it was either a genius, or rather a person familiar with the military history of Greece, Macedonia and Rome. He used the previous experience of Flemish city militias using the phalanx. But the Swiss needed a battle formation that would allow the soldiers to repel enemy attacks from all sides. First of all, such tactics were intended to combat heavy cavalry. The battle was absolutely helpless against the shooters. Its vulnerability to projectiles and arrows was explained by the fact that in the 14th century, solid metal armor of the Gothic type began to be used everywhere. Its fighting qualities were so high that warriors, both mounted and on foot, who had such equipment, little by little began to abandon large shields, replacing them with small “fist” shields - convenient for fencing.
In order to pierce such armor as efficiently as possible, gunsmiths came up with new variants of weapons: godendags (about him here ), war hammers, halberds... The fact is that short-shafted axes and axes (extremely widely used throughout the military history of mankind) for piercing solid armor did not have enough swing radius, therefore inertia and impact force, their penetrating power was small, and in order to pierce a cuirass or helmet of armor of the 14th-15th centuries, it was necessary to deliver a whole series of blows (of course, there were very physically strong people who with Short-shafted weapons were also successfully used, but there were few of them). Therefore, they invented a weapon of combined action on a long shaft, which increased the radius of the blow and, accordingly, due to the accumulated inertia, its strength, which was also facilitated by the fact that the warrior struck with both hands. This was an additional reason for abandoning the shields. The length of the pike also forced the fighter to manipulate it with both hands; for pikemen, the shield became a burden.
For their own protection, unarmored infantry shooters used large shields, forming them into a solid wall or acting individually (the most famous example is the large shield of the Genoese crossbowmen - “paveza”).
Traditionally, the invention of the halberd is attributed to the Swiss. But in no country could such weapons suddenly appear, right away. This requires long-term combat experience and a powerful production base, available only in large cities. The most favorable conditions for improving weapons at that time were in Germany. The Swiss did not invent, but systematized the use of halberds and pikes in the ranks.
Swiss pikeman and halberdier of the 15th-16th centuries. 
Battles could be of different sizes and were squares of 30, 40, 50 warriors in width and depth. The arrangement of the infantrymen in them, most likely, was as follows: the first two ranks were made up of pikemen, dressed in reliable protective armor. The so-called “one-and-a-half” (helmet, cuirass, shoulder pads, legguards) or “three-quarter” (helmet, cuirass, shoulder pads, elbow pads, leg guards and combat gloves) Their peaks were not particularly long and reached 3–3.5 meters. They held the weapon with both hands: the first row - at hip level, and the second - at chest level. The warriors also had melee weapons. Since they were the ones who took the main blow from the enemy, they were paid more than everyone else. The third rank was made up of halberdiers, who struck at those who had made their way close to the first ranks of the enemy: slashing from above or piercing through the shoulders of the front warriors. Behind them stood two more ranks of pikemen, the peaks of which were thrown to the left side, according to the Macedonian model, so that when carrying out attacks, the weapons would not collide with the peaks of the warriors of the first two ranks. The fourth and fifth rows worked respectively, the first - at the level of the hip, the second - at the chest. The length of the pikes of the warriors of these ranks was even greater, reaching 5.5–6 meters. The Swiss, although they had halberdiers in the third rank, did not use the sixth attack row. This was due to the fact that the warriors would be forced to strike with pikes at the upper level, that is, from the head, over the shoulders of those in front, and in this case, the pikes of the sixth row fighters would collide with the halberds of the third rank, also working at the upper level, and limit their actions to that , that halberdiers would be forced to strike only from the right side. Sometimes the warriors inside the battle changed places, depending on the developing combat situation. The commander, to strengthen the frontal ramming attack, could remove the halberdiers from the third rank and transfer them to the rear. All six ranks of pikemen would then be deployed along the lines of the Macedonian phalanx. Warriors armed with halberds could also be in the fourth rank. This option was convenient when defending against attacking cavalry. In this case, the pikemen of the first rank knelt, sticking their pikes into the ground and pointing their tips towards the enemy horsemen, the 2nd and 3rd, 5th and 6th ranks struck, as described above, and the halberdiers, placed in the fourth rank, they had the opportunity to freely work with their weapons, without fear of interference from the first rank. In any case, the halberdier could reach the enemy only when he, having overcome the palisade of peaks, cut into the ranks of the battle. The halberdiers controlled the defensive functions of the formation, extinguishing the impulse of the attackers, while the attack was carried out by the pikemen. This order was repeated by all four sides of the battle.
Those in the center created pressure. Since they did not participate in hand-to-hand combat, they received the least pay. Their level of training was low; poorly trained militias could be used here. In the center were the battle commander, standard bearers, drummers and trumpeters, who gave signals for this or that maneuver. 
If the first two ranks of the battle could withstand enemy fire, then all the others were absolutely defenseless from overhead fire. Therefore, the line infantry simply needed cover from shooters - crossbowmen or archers, first on foot, and later on horseback. In the 15th century, arquebusers were added to them.
Swiss combat tactics were very flexible. They could fight not only as a battle, but also as a phalanx or wedge. Everything depended on the commander’s decision, terrain features and battle conditions.
The Swiss battle received its first baptism of fire at Mount Morgarten (1315). The Swiss attacked the Austrian army, which was on the march, having previously disrupted its ranks with stones and logs dropped from above. The Austrians were defeated. In the battle of Laupen (1339), three battles took part, supporting each other. Here their excellent fighting qualities were demonstrated in a battle with the phalanx of the militia of the city of Freisburg, whose formation was broken through by a battle that was not afraid of flanking. But the heavy cavalry was unable to break through the Swiss battle formation. Carrying out scattered attacks, the horsemen were unable to break the formation. Each of them had to fend off blows from at least five people at once. First of all, the horse died, and the rider, having lost him, no longer posed a danger to the Swiss battle.
At Sempach (1386), Austrian cavalrymen tried to defeat the battle by dismounting. Having the best defensive equipment, they attacked the Swiss with a phalanx, probably in the corner of the formation, and almost broke through it, but the situation was saved by the second approaching battle, which struck the flank and rear of the Austrians; they fled.
However, the Swiss should not be considered invincible. It is known that they also suffered defeats, for example, at Saint-Jacob on Birce (1444) from the Dauphin (then king) Louis XI, who used mercenary troops, the so-called “armagnac freemen”. The point is different, according to statistics, the Swiss infantry during its heyday won 8 out of 10 battles in which it participated.
As a rule, the Swiss went into battle in three battle squads. The first detachment (forhut), marching in the vanguard, determined the point of attack on the enemy formation. The second detachment (Gevaltshaufen), instead of lining up with the first, was located parallel to it, but at some distance to the right or left behind. The last detachment (nahut) was located even further away and often did not engage in battle until the effect of the first attack was clear and could thus serve as a reserve.
In addition, the Swiss were distinguished by the most severe discipline in battle, atypical for medieval armies. If suddenly a warrior in the battle line noticed an attempt to escape by a comrade standing nearby, or even a hint of it, he was obliged to kill the coward. Without doubt, thought, quickly, without giving even a small chance of panic. A fact blatant for the Middle Ages: the Swiss practically did not take prisoners; the punishment for a Swiss warrior who captured an enemy for ransom was one thing - death. And in general, the harsh highlanders did not bother: any offense, even insignificant in modern eyes, that violated military discipline (in their understanding, of course) was followed by the quick death of the criminal. It is not surprising that with such an attitude to discipline, the “Schvis” (a contemptuous nickname for the Swiss among European mercenaries) were an absolutely ruthless, terrible enemy for any opponent.
Over a century of continuous battles, the Swiss infantry has so honed its method of warfare that it has turned into a magnificent fighting machine. Where the commander’s abilities, as such, did not have a big role. Before the Swiss infantry, such a level of tactical perfection was achieved only by the actions of the Macedonian phalanx and Roman legions. But soon the Swiss had a competitor - the German Landsknechts, created by Emperor Maximilian precisely in the image and likeness of the infantry of the “free cantons”. When the Swiss fought with a band of Landsknechts, the brutality of the battle exceeded all reasonable limits, so the meeting of these opponents on the battlefield as part of the warring parties received the name “Bad War” (Schlechten Krieg) among contemporaries.
Engraving by Hans Holbein the Younger "Bad War" 
But the famous European two-handed sword “zweihander” (you can read about it here), the size of which sometimes reached 2 meters, was actually invented by the Swiss back in the 14th century. The methods of action of these weapons were very precisely defined in his book by P. von Winkler:
"Two-handed swords were used only by a small number of very experienced warriors (Trabants or Drabants), whose height and strength should exceed the average level and who had no other purpose than to be "Jouer d"epee a deus mains." These warriors, being at the head of the detachment, break the shafts of the pikes and pave the way, overturning the advanced ranks of the enemy army, followed by other foot soldiers along the cleared road. In addition, Jouer d'epee accompanied nobles, commanders-in-chief, and commanders in skirmishes; they paved the way for them, and if the latter fell, they guarded them with the terrible swings of their swords until they rose with the help of pages."
The author is absolutely right. In the ranks, the owner of the sword could take the place of a halberdier, but such weapons were very expensive and their production was limited. In addition, the weight and size of the sword did not allow everyone to wield it. The Swiss trained specially selected soldiers to work with such weapons. They were highly valued and highly paid. Usually they stood in a row at a sufficient distance from each other in front of the advancing battle and cut the shafts of the enemy’s exposed pikes, and, if they were lucky, they cut into the phalanx, causing confusion and disorder, which contributed to the victory of the battle that followed them. In order to protect the phalanx from swordsmen, the French, Italians, Burgundians, and then the German landsknechts were forced to prepare their warriors who knew the technique of fighting with such swords. This led to the fact that before the start of the main battle, individual duels with two-handed swords often took place.
To win such a fight, a warrior had to have high-class skills. Here, skill was required to fight both at long and close distances, to be able to combine wide chopping blows at a distance with instant interceptions of the sword blade in order to reduce this distance, manage to approach the enemy at a short distance and hit him. Piercing blows and sword strikes to the legs were widely used. Fighting masters used techniques of striking with body parts, as well as grappling and sweeping.
You see how much good and light the Swiss infantry brought to Europe :-)
Sources
Taratorin V.V. "History of combat fencing" 1998
Zharkov S. "Medieval cavalry in battle." Moscow, EKSMO 2008
Zharkov S. "Medieval infantry in battle." Moscow, EXMO 2008
In 1458, near the Buda fortress on the ice of the Danube River, the burghers and nobility proclaimed Matyas Hunyadi, the 14-year-old heir of the talented commander Janos Hunyadi, king of Hungary. As a result of the national liberation revolution, the teenager, thrown into prison by his competitors in the fight for the Hungarian crown, came to power. Thus appeared a commander whose army would become one of the most combat-ready armies of Medieval Europe.
Matyash's father, Janos, was a good warrior and strategist. Thanks to him, the Balkan Peninsula successfully held back the invasion of the Ottomans for a long time, and only death from the plague ended the chronicle of successful battles of this historical figure. Young Matyash was drawn to reading and, as a child, became engrossed in the works of Julius Caesar. This is exactly how the idea of creating a professional army, later called "Black Army"(Fekete Sereg).
Historians disagree about the origin of the term "Black Army". The name apparently was not given during King Matthias's lifetime, but appears in documents written immediately after his death. There are various theories that the soldiers were dressed in black or wore black ribbons on their shoulders while mourning King Matthias. Another theory is that the name comes from the black breastplate worn by Captain František Hag, or, alternatively, the name is linked to the nickname of another Black Army officer, Captain Janos "The Black" Haugwitz.
And, if in other countries warriors in peacetime could be farmers, bakers, masons, then the “Black Army” was a highly paid army of professionals who were engaged in purely military affairs. The backbone of the army consisted of 6-8 thousand mercenaries; in 1480 this figure increased to 20 thousand, and in 1487 it amounted to 28 thousand. Mostly, the soldiers were Bohemians, Serbs, Poles, Germans, and, starting from the 80s, Hungarians. The key to the victories of the “Black Army” was the widespread use of firearms. One in four soldiers carried an arquebus, an unusual ratio in armies of the time. Even at the beginning of the 16th century, only 10% of European armies used firearms.
The basis of the troops was infantry, artillery, light and heavy cavalry. The heavy cavalry protected the lightly armed infantry and artillery, while the rest of the army made surprise attacks on the enemy. The river fleet consisted of galleys, boats and small ships that could sail along the Danube, Tisza and Sava. In 1475, artillery was installed on river barges: mortars and bombards. In 1479, the fleet consisted of 360 ships, and the crew was 2,600 sailors and 10 thousand soldiers on board.
A regular paid army also had its drawbacks - in case of delay in payment, some soldiers could leave the battlefield or start a riot. However, this was compensated by the high level of training of the soldiers who served in it. For 30 years, the “Black Army” restrained the expansion of the Ottomans into Western Europe, contributed to the unification of Hungary and the conquest of new territories, thus creating a powerful state in the center of Europe, capable of resisting external enemies.
At the intersection of antiquity and the Middle Ages, the main concern of man, as before, was the protection of his life. Over time, the process of metal processing developed and various crafts improved, as a result of which newer and more modern types of weapons began to be invented, and with it improved protective equipment appeared. One of the most used and famous at the beginning of the Middle Ages was the medieval bladed weapon. These were considered daggers, swords, and bows. There was also specialized protection in the form of a shield and armor.
Protective equipment in the Middle Ages
It is generally accepted that the Celts first invented chain mail armor back in 500 BC. Gradually, as a result of the victorious movement of the Celtic army across the expanses of Europe, this armor appeared in all settlements of the medieval continent. Over time, this type of protective armor was significantly improved - metal plates were added to its design, which protected the owner from slashing and sliding blows. This is where plate armor originated.
However, even with the urgent need for protection from enemy weapons, not all warriors living in the Middle Ages could afford to have medieval protective equipment. Rich residents of those times ordered individual armor that was made exclusively for them. Ordinary soldiers purchased ready-made equipment and then adjusted it to their parameters.
It should be noted that high-quality armor could protect against damage from swords, arrows, and, sometimes, from initial types of firearms in almost one hundred percent of cases. If we talk about the practicality of protective equipment, they began to learn to wear it in their youth, since the mass of such armor was more than 30 kg.
Types of medieval weapons
The basic weapon of a warrior in the Middle Ages was, as before, a sword. These medieval weapons were presented in a huge number of types. The sword could be sharp on both sides, with one blade, with a sharp or flat end, have a ribbed or rounded shape, and of different lengths. What weapon to use depended on what combat tactics the commander chose, as well as on the specific skills of the soldiers.
However, even though there were many types of bladed weapons in the form of swords in those distant times, they all had common details that distinguished these weapons from others. These features were the pommel and knob, as well as the crosspiece and hilt
Even such wide popularity of the sword did not make it possible for every warrior to have it. They were used only by wealthy people, because the method of its implementation was too complex, required a lot of time, effort and human labor, and therefore was very expensive. Also, the common man was not allowed to carry these weapons at all. It should also be noted that in the Middle Ages, weapons such as a combat sword, which was intended for combat, became a true symbol of the valor and courage of a warrior.
Along with the sword, other weapons were used - throwing and striking. Siege weapons developed alongside construction technologies. As a result of the invention of gunpowder by the Chinese in the 14th century, a new type appeared called firearms.
This discovery made a colossal revolution in the conduct of combat operations, which received completely new techniques.