The early modern period is often cited as a military revolution. Though some scholars describe an evolutionary rather than a revolutionary process, it is undeniable that European battlefields of the 16th and 17th centuries witnessed major changes in tactics and equipment. The supremacy of cavalry was finally ended by infantry advances. Artillery, siegecraft, and naval warfare also experienced great changes during this period.1. Landsknecht Pike SquaresBad War by Hans Holbein, 1520. Source: Grafische Sammlung AlbertinaImitation is the most sincere form of flattery and the Landsknechts epitomised it. Modelled on the Swiss mercenaries who dominated European battlefields at the turn of the 16th century, they fought in similar blocks of pikemen and halberdiers. The main body was a pike square supplemented by halberdiers and Doppelsoldners. The latter were volunteers who took positions of extra risk but received double pay as a result. They could be armed with an arquebus or crossbow but the most popular depiction is of them carrying the zweihander, the distinctive double-handed sword that is still popular in games like Warhammer.The Landsknecht were easily recognisable by their distinctive multicolored dress, the result of soldiers repairing their clothing with whatever material was at hand. Later it became a way to display wealth and experience, with a variety of color and material indicating a particularly well-off or well-travelled Landsknecht. In addition to their primary weapon, most Landsknechts also carried a katzbalger, a shortsword that became one of their signatures.Unlike the Swiss, their discipline left much to be desired. Commonly employed by the Holy Roman Empire, Landknechts were famous for going on the rampage after taking a city, notoriously sacking Rome in 1527. They were viewed as dangerous, unpredictable, and mutinous if unpaid. They still remained a core component of Central European armies despite this mixed reputation. Their status was also threatened by units such as the Spanish tercios. Although Landsknechts were much cheaper to raise, train, and maintain than the expensive Spanish infantry, the role of the mercenary declined as states increasingly looked towards making a professional standing army.2. Spanish Tercios: Pike and Shot TacticsSpanish Tercio Formation at the 1600 Battle of Nieuwpoort. Source: Atlas van LoonThe Spanish tercios were the most famous infantry in the 16th/17th centuries. Nicknamed the Invincibles or the Immortals, they were feared across Europe for their iron discipline. Spanish infantry were seen as the gold standard and rival powers did their best to emulate their training and tactics.The tercios were the epitome of pike and shot tactics, relying on a cohort of pikemen and musketeers working together. The musketeers provided the offensive capability for the formation while the pikemen protected them from cavalry and infantry attacks. Early iterations also featured swordsmen who could be used to break up enemy pike formations. It was difficult to manoeuvre and an easy target for enemy artillery. The 17th century saw Spanish formations engaging smaller, agile enemy units that focused on firepower over sheer mass.The tercios reputation for invincibility was finally shattered at the Battle of Rocroi against France in 1643, but even there while the Spanish lost the battle, the tercios withstood hours of artillery bombardment and attacks by infantry and cavalry. The tercios were also feared for their dangerous actions when mutinying. Unpaid tercios in Flanders were notorious for their rampages after capturing cities, sometimes taking days before officers could restore order. They became something of an international force as Spain found itself embroiled in larger conflicts, forced to recruit from everywhere to keep units up to strength. The officers and core of the tercios remained Spanish but in Flanders they recruited Italians, Germans, Irish, Scotsmen, Walloons, and Flemings.3. Military Reforms and ProfessionalizationA Soldier Loading His Caliver by Jacob de Gheyn, 1607. Source: The Morgan Library and MuseumThe increasing scale of warfare in early modern Europe contributed to a resulting surge in professionalism. Military reforms were instituted that slowly broke the supremacy of the tercio just as pikes had reduced the prestige of cavalry. Military theorists scoured ancient manuals for inspiration to defeat major powers such as Habsburg Spain or the Ottoman Empire.Many of the initial reforms drew on ancient Macedonian and Roman techniques. Close order drill (still a cornerstone of basic military training) was instituted, enabling soldiers to act in unison, enabling increasingly complicated formations and maneuvers on the battlefield. It also broke down basic military movements such as loading a musket or hefting a pike into a series of small imitable movements, a method of instruction still used by armies today. Soldiers became specialists in their chosen weapon, be that a pike or musket.Another ancient drill that experienced a resurgence was that of the countermarch. Initially used by the Romans for slingers, peltasts, or archers, the same technique could be applied to troops using muskets or arquebuses. The front rank would fire before turning and marching down the gaps in the files to the rear of the formation. There they could reload while the next rank presented their weapons. This was mimicked by horsemen in techniques such as the caracole where the front rank would discharge their firearms before galloping to the rear to reload, allowing the next rank to push forward and fire. Professionally trained troops had a much greater advantage over hastily raised levies or militias.4. Winged Hussars and Hakkapeliitta: Shock and AweHussar by Micha Kulea, 19th century. Source: Lithuanian Museum of ArtTwo distinct types of cavalry further east were the Polish winged hussars and the Finnish Hakkapelitta. The winged or Polish hussars were a distinctive type of lancer known for their elaborate wings worn on the back of their armor. Unlike hussars in other countries, used mostly as light cavalry and unarmored, Polish hussars served as heavy cavalry, used as shock troops to shatter enemy formations.Polish hussars fought in nearly every battle of the Polish-Lithuanian Commonwealth from the mid-1500s to the early 1700s. They are most well known for their participation in the Siege of Vienna in 1683 where they formed part of the largest cavalry charge in history. Led by King Jan III Sobieski, the Polish hussars and thousands of allied cavalry struck the decisive blow to break the Ottoman siege of the Austrian capital.A different sort of cavalry was the Finnish hakkapeliitta. The Finns fought as part of the Swedish Army. They employed similar tactics to the hobelar or reiver cavalry that had been used in Britain and Ireland until the 1600s. The hakkapeliitta were a versatile type of light cavalry that fulfilled all the duties of skirmishing, raiding, and reconnaissance that light cavalry were tasked with. They were also useful in battle, famed for their speed and aggressiveness. Their name is derived from their battle cry, hakkaa plle, Finnish for cut them down!The hakkapeliitta fought with the Swedish Army in Germany, Estonia, Livonia, Poland, Bohemia. During the Thirty Years War, they announced themselves on the central European stage when King Gustavus Adolphus led them to a crushing victory over the Imperial Army at the Battle of Breitenfeld in 1631.5. Black Riders and Dragoons: Firearm CavalryPappenheim Cuirassiers by Hendrik Jacobus Vinkhuijzen, 1632. Source: New York Public LibraryThe most common type of cavalry found in central Europe were Black Riders (Reiters). In some ways a precursor to the dragoon, they marked the transition of cavalry from melee weapons to firearms. Reiters were armored but did not wear a full suit of armor like a knight. They carried swords but the main weapon was the pistol. The aforementioned caracole was their favored tactic, continually harassing infantry with volleys of pistol fire until (according to theory) the enemy formation disintegrated. The Dutch commander Maurice of Nassau aptly demonstrated their potential when he defeated Spanish infantry and cavalry with a mostly cavalry force at Turnhout in 1597.While the name reiter shows a predominantly Germanic origin, many reiters served as mercenaries in foreign armies, thus exporting the term to different languages. A more international version of firearm cavalry were dragoons. Dragoons were a middle ground between cavalry and infantry. They moved on horseback but dismounted to fight. Cheaper to raise than cavalry, they were jacks of all trades, used as both infantry and cavalry depending on the situation.This mixed origin made dragoons a flexible type of soldier but inferior to true cavalry in a melee due to their smaller horses and equipment. Against numerically superior infantry they could always retreat. Dragoons struggled for decades to raise their social status. In the Swedish army they were referred to as laborers on horseback, but by the late 1700s most dragoon regiments had become indistinguishable from that of other cavalry units.6. Firepower Over ManpowerBattle of Vienna by Frans Geffels, 1690. Source: Wien MuseumIn the 17th century, reformers such as Maurice of Nassau in the Netherlands and Gustavus Adolphus in Sweden made their own modifications to the Spanish tercio which was still seen as the infantry gold standard. Both were from smaller nations that could not rely on large reserves of manpower like France, Spain, or Russia. Maurice emphasised broader narrower formations that brought more firepower to bear on a target, reducing ranks of musketeers from ten deep to six. He also utilized smaller formations than the Spanish. His theories proved effective when he defeated a Spanish army in the field at Nieuwpoort in 1600, a rare accomplishment at the time.Gustavus Adolphus pioneered his own aggressive tactics. Like Maurice, he reduced his musketeer ranks, prioritising the shock of a mass salvo. Musketeers would pack together so three ranks could fire at once before the enemy were charged. Swedish doctrine also emphasized the shock effect of cavalry. Unlike rivals who would retreat to reload, Swedish cavalry would charge in tight packed formations, firing their pistols close in before crashing into the enemy. Tactics like these enabled the outnumbered Swedes to defeat larger armies and make up for their lack of numbers.Other countries had their own innovations. Further east, Russian armies would use improvised fortifications to make a moving fort while other eastern armies in Europe prioritized cavalry. The terrain also dictated the tactics and style of fighting. Armor remained popular in eastern Europe because of the Tatars and Ottomans as they still used bows alongside firearms. The military revolution continued throughout the 1600s with innovations such as the bayonet, which enabled infantrymen to use their firearms as an improvised pike in melee combat, further enhancing their superiority over cavalry.