Military history
They invaded Vietnam (northern Vietnam had been in Chinese control since the Han dynasty), fighting the troops of Champa, who had cavalry mounted on elephants. After decades of economic turmoil and a failed invasion of Korea, the Sui collapsed and was followed by the Tang dynasty, who fought with various Turkic groups, the Tibetans of Lhasa, the Tanguts, the Khitans, and collapsed due to political fragmentation of powerful regional military governors (jiedushi). The innovative Song dynasty followed next, inventing new weapons of war that employed the use of Greek Fire and gunpowder (see section below) against enemies such as the Jurchens.

The Mongols under Genghis Khan, Ögedei Khan, Möngke Khan, and Kublai Khan conquered most of Eurasia. They took over China, Persia, Turkestan, and Russia. After Kublai Khan took power and created the Yuan dynasty, the divisions of the empire ceased to cooperate with each other, and the Mongol Empire was only nominally united.
In New Zealand, prior to European discovery, oral histories, legends and whakapapa include many stories of battles and wars. Māori warriors were held in high esteem. One group of Polynesians migrated to the Chatham Islands, where they developed the largely pacifist Moriori culture. Their pacifism left the Moriori unable to defend themselves when the islands were invaded by mainland Māori in the 1830s.
They proceeded to massacre the Moriori and enslave the survivors. Warrior culture also developed in the isolated Hawaiian Islands. During the 1780s and 1790s the chiefs and alii were constantly fighting for power. After a series of battles the Hawaiian Islands were united for the first time under a single ruler who would become known as Kamehameha I.

Gunpowder warfare: After gunpowder weapons were first developed in Song dynasty China (see also: Technology of the Song dynasty), the technology later spread west to the Ottoman Empire, from where it spread to the Safavid Empire of Persia and the Mughal Empire of India. The arquebus was later adopted by European armies during the Italian Wars of the early 16th century.
This all brought an end to the dominance of armored cavalry on the battlefield. The simultaneous decline of the feudal system—and the absorption of the medieval city-states into larger states—allowed the creation of professional standing armies to replace the feudal levies and mercenaries that had been the standard military component of the Middle Ages.
In Africa, Ahmad ibn Ibrihim al-Ghazi, was the first African commander to use gunpowder on the continent in the Ethiopian–Adal War, that lasted for fourteen years (1529–1543).
The period spanning between the 1648 Peace of Westphalia and the 1789 French Revolution is also known as Kabinettskriege (Princes' warfare) as wars were mainly carried out by imperial or monarchics states, decided by cabinets and limited in scope and in their aims. They also involved quickly shifting alliances, and mainly used mercenaries.
Over the course of the 18th–19th centuries all military arms and services underwent significant developments that included a more mobile field artillery, the transition from use of battalion infantry drill in close order to open order formations and the transfer of emphasis from the use of bayonets to the rifle that replaced the musket, and virtual replacement of all types of cavalry with the universal dragoons, or mounted infantry.

Military Revolution: The Military Revolution is a conceptual schema for explaining the transformation of European military strategy, tactics and technology in the early modern period. The argument is that dramatic advances in technology, government finance, and public administration transformed and modernized European armies, tactics, and logistics. Since warfare was so central to the European state, the transformation had a major impact on modernizing government bureaucracies, taxation, and the national economy. The concept was introduced by Michael Roberts in the 1950s as he focused on Sweden 1560–1660. Roberts emphasized the introduction of muskets that could not be aimed at small targets, but could be very effective when fired in volleys by three ranks of infantry soldiers, with one firing while the other two ranks reloaded. All three ranks march forward to demolish the enemy. The infantry now had the firepower that had been reserved to the artillery, and had mobility that could rapidly advance in the battlefield, which the artillery lacked. The infantry thereby surpassed the artillery in tactical maneuvering on the battlefield. Roberts linked these advances with larger historical consequences, arguing that innovations in tactics, drill and doctrine by the Dutch and Swedes 1560–1660 led to a need for more and better trained troops and thus for permanent forces (standing armies). Armies grew much larger and more expensive. These changes in turn had major political consequences in the level of administrative support and the supply of money, men and provisions, producing new financial demands and the creation of new governmental institutions. "Thus, argued Roberts, the modern art of war made possible—and necessary—the creation of the modern state". In the 1990s the concept was modified and extended by Geoffrey Parker, who argued that developments in fortification and siege warfare caused the revolution. The concept of a military revolution based upon technology has given way to models based more on a slow evolution in which technology plays a minor role to organization, command and control, logistics and in general non-material improvements. The revolutionary nature of these changes was only visible after a long evolution that handed Europe a predominant place in warfare, a place that the industrial revolution would confirm.
The concept of a military revolution in the sixteenth and seventeenth centuries has received a mixed reception among historians. Noted military historians Michael Duffy and Jeremy Black have strongly criticised it as misleading, exaggerated and simplistic.

Industrial warfare: As weapons—particularly small arms—became easier to use, countries began to abandon a complete reliance on professional soldiers in favor of conscription. Technological advances became increasingly important; while the armies of the previous period had usually had similar weapons, the industrial age saw encounters such as the Battle of Sadowa, in which possession of a more advanced technology played a decisive role in the outcome. Conscription was employed in industrial warfare to increase the number of military personnel that were available for combat. Conscription was notably used by Napoleon Bonaparte and the major parties during the two World Wars.
Total war was used in industrial warfare, the objective being to prevent the opposing nation to engage in war. Napoleon was the innovator. William Tecumseh Sherman's "March to the Sea" and Philip Sheridan's burning of the Shenandoah Valley during the American Civil War were examples. On the largest scale the strategic bombing of enemy cities and industrial factories during World War II was total warfare.

Modern warfare: Since the 1940s, preparation for a major war has been based on technological arms races involving all sorts of new weapons systems, such as nuclear and biological, as well as computerized control systems, and the opening of new venues, such as seen in the Space race involving the United States, the Soviet Union, and more recently, China.
Modern war also saw the improvement of armored tank technology. While tanks were present in the First World War, and the Second World War, armored warfare technology came to a head with the start of the Cold War. Many of the technologies commonly seen on main battle tanks today, such as composite armor, high caliber cannons, and advanced targeting systems, would be developed during this time.
A distinctive feature since 1945 is the absence of wars between major powers—indeed the near absence of any traditional wars between established countries. The major exceptions were the Indo-Pakistani War of 1971, the Iran–Iraq War 1980–1988, and the Gulf War of 1990–91. Instead actual fighting has largely been a matter of civil wars and insurgencies. The most recent example of a war between two nation states would be the 2022 Russian invasion of Ukraine.

See also: 

Notes and references: 

Further reading: 

External links: 
International Bibliography of Military History of the International Commission of Military History – from Brill.nl
H-WAR, daily discussion group for military historians – from Michigan State University Department of History, H-Net Humanities & Social Sciences Online
Web Sources for Military History – from AmericanHistoryProjects.com
Military History Encyclopedia on the Web