Early modern warfare

Early modern warfare is the era of warfare during early modern period following medieval warfare. It is associated with the start of the widespread use of gunpowder and the development of suitable weapons to use the explosive, including artillery and firearms; for this reason the era is also referred to as the age of gunpowder warfare (a concept introduced by Michael Roberts in the 1950s).

Fortification techniques evolved rapidly due to the development of artillery. Firearms revolutionized warfare, diminishing the role of aristocracies and heavy cavalry. Early firearms, like arquebuses and muskets, gradually replaced bows and crossbows, leading to the introduction and decline of plate armor as firearms became more effective. Flintlock muskets became dominant by the 1690s, and the invention of the bayonet combined pikes and muskets, transforming infantry into the most crucial military force. Warfare also saw a shift towards larger armies and more devastating conflicts. The rise of centralized states and bureaucracies supported the new, massive armies, while the use of mercenaries declined. Military formations adapted to these changes. Infantry relied on columns, lines, and squares for battle, while cavalry transitioned to lighter roles focused on scouting and flanking. Despite the decline in heavy cavalry's dominance, cavalry charges remained effective under specific conditions, particularly against undisciplined infantry. The Age of Sail (usually dated as 1571–1862) was a period roughly corresponding to the early modern period and gunpowder dominated the era's naval tactics, including the use of gunpowder in naval artillery.

Wars became longer and more destructive, often causing widespread civilian suffering:

In Europe, Medieval castles were replaced by the "Italian style" fortresses, known for low, thick, sloping walls and star-shaped designs with bastions. However, by the mid-18th century, polygonal forts emerged to counter the power of explosive shells.

The period from 1501 to 1800 saw a rapid advance in techniques of fortification in Europe. Whereas medieval castles had relied on high walls to keep out attackers, early modern fortifications had to withstand artillery bombardments. To do this, engineers developed a style of fortress known as the "Italian style" or trace Italienne. These had low, thick, sloping walls, that would either absorb or deflect cannon fire.

In addition, they were shaped like stars, with bastions protruding at sharp angles. This was to ensure that every bastion could be supported with fire from an adjacent bastion, leaving no dead ground for an attacker to take cover in. These new fortifications quickly negated the advantages cannon had offered to besiegers.

In response to the vulnerabilities of star forts, military engineers evolved a much simpler but more robust style of fortification. A polygonal fort is a fortification in the style that evolved around the middle of the 18th century, in response to the development of explosive shells. The complex and sophisticated designs of star forts that preceded them were highly effective against cannon assault, but proved much less effective against the more accurate fire of rifled guns and the destructive power of explosive shells. The polygonal style of fortification is also described as a "flankless fort". Many such forts were built in the United Kingdom and British Empire during the government of Lord Palmerston, and so they are also often referred to as Palmerston forts. Fort Tas-Silġ is an example of a British polygonal fort.

The power of aristocracies vis à vis states diminished throughout Western Europe during this period. Aristocrats' 200- to 400-year-old ancestral castles no longer provided useful defences against artillery. The nobility's importance in warfare also eroded as medieval heavy cavalry lost its central role in battle. The heavy cavalry—made up of armoured knights—had begun to fade in importance in the Late Middle Ages. The English longbow and the Swiss pike had both proven their ability to devastate larger armed forces of mounted knights. However, the proper use of the longbow required the user to be extremely strong, making it impossible to amass very large forces of archers.