Up until the 19th century, much of military tactics was confined to battlefield tactics, concerned with maneuvering units in battle in open terrain. In current military thought, tactics is the operational application of forces to a situation. This is different from military strategy, which is more concerned with long-term results.

Specialized tactics exist for many situations, from situations as small as securing a room to large-scale operations such as establishing air superiority in aircraft carrier battles. Today, military tactics are employed on all levels of command, from individual and group up to entire armed forces. Indeed, the units used in warfare have always been a reflection of current military tactics, and their size and composition have varied accordingly.

Common military tactics include frontal assaults, attempts to flank the enemy, keeping troops in reserve and the use of ambushes. Often deception in the form of camouflage, or misdirection using decoys, are used to confuse the enemy.

Examples of reconnaissance include patrolling by troops, ships, submarines, or aircraft, or by setting up covert observation posts. Reconnaissance may also be carried out by satellites or unmanned aircraft.

Reconnaissance seeks to find a range of information about an enemy. This includes their locations, numbers, and intentions. Thus reconnaissance is a fundamental tactic which helps to build an intelligence picture.

There are several different types of patrol each with a different objective. The most common is to collect intelligence by carrying out a reconnaissance patrol. Such a patrol may try to remain covert and observe an enemy without themselves being detected. Other reconnaissance patrols are overt, especially those that interact with the civilian population.

A fighting patrol is a group with sufficient size (usually platoon or company) and resources to raid or ambush a specific enemy. It primarily differs from an attack in that it is not the aim to hold ground.

A clearing patrol is a brief patrol around a newly occupied defensive position in order to ensure that the immediate area is secure.

A number of patrols may be deployed to 'screen' a large area. This type of patrol is used by armored formations in desert theatres, and also by ground troops operating in urban areas.

Care must be taken by the ambush commander to ensure that fire from any weapon cannot inadvertently hit any other friendly unit.

After the firefight has been won, the now compromised ambush patrol will need to leave the area as soon as practical. Before this is done it is a common practice to clear the killing zone by checking bodies for intelligence, taking prisoners, and treating any enemy wounded. If communication orders permit, a brief contact report may be sent. This done, the ambush patrol will leave the area by a pre-determined route.

Before the 19th century, a frontal assault against a line could be effective when conducted by horse cavalry. However, as the accuracy and range of firearms increased, this procedure proved increasingly suicidal.

This style of combat was used heavily in the American Civil War, for example. The type of militaries used as well as the terrain lended themselves to direct frontal assault, and most of the battles of the Civil War were fought in this manner.

Frontal assaults were also the cause of massive casualties in the trench warfare of World War One. In many cases, frontal assaults were made by thousands of men towards trenches defended by machine gun emplacements, with predictable and tragic results.

Most infantry combat, on every scale, is based in some fashion on this military tactic and it is commonly used by aircraft as well. It was vaguely described in Sun Tzu's The Art of War, but he argued that it was best to allow the enemy a path to escape, as he felt the target army would fight with more ferocity when completely surrounded. However, the pincer is commonly employed in modern warfare.

Lines of circumvallation generally consist of earth ramparts and entrenchments that encircle the besieged city. The line of circumvallation can be used as a base for launching assaults against the besieged city or for constructing further earthworks nearer the city.

In cases where the besieging army is threatened by a field army allied to the city, the besieging army may construct a second line of fortifications between themselves and the outside enemy parallel to the lines of circumvallation, known as 'lines of contravallation'. This envelopes the city in a double line of fortifications and doubly protects the besiegers. In turn, the besiegers may find themselves besieged within their lines of circumvallation and contravallation.

The circumvallation and contravallation tactic has the advantage of making it possible to redirect troops from the siege (now reinforced by the first wall of fortifications) to the defense of the besieging army itself.

Sieges are as old as warfare itself, with towns in the Middle East from the dawn of civilization having city walls. There are a number of tales of sieges in ancient sources, such as the siege of Jericho in the Old Testament or the siege of Troy described by Homer in the Iliad. An astonishing number and variety of sieges formed the core of Julius Caesar's conquest of Gaul.

The universal method for defending against siege is the use of fortifications, principally walls and ditches, and a sufficient supply of food and water. In the European Middle Ages, virtually all large cities had city walls -- Dubrovnik in Dalmatia is an impressive and well-preserved example -- and more important cities had citadels, forts or castles. Great effort was expended to ensure a good water supply inside the city in case of siege. In some cases, long tunnels were constructed to carry water into the city. Complex systems of underground tunnels were used for storage and communications in medieval cities like Tábor in Bohemia, and in Vietnam during the Vietnam war. In modern times, trenches have replaced walls, and bunkers have replaced castles.

The significance of the classical siege has been declining since the great Swedish white-elephant fortification of Karlsborg was completed in 1869. One single fortified stronghold, whatever the scale (Karlsborg was conceived as a reserve capital for Sweden), was no longer decisive. Whole cities have increasingly come under siege, fortified or not (eg Leningrad), and even, using blockades and the related "low-impact" attritional weapon of sanctions, whole countries (for instance, Cuba, Libya and Iraq).

The Blitzkrieg of the Second World War showed, however, that fixed fortifications are easily defeated by maneuver instead of frontal assault or long sieges. Battles that would have taken weeks of siege could now be avoided with the careful application of air power (such as the German paratrooper capture of Fort Eban, Belgium, early in World War II). The most important sieges of the Second World War were on the Eastern Front where bloody urban warfare marked the battles of Leningrad and Stalingrad. In these battles, the ruins of an urban landscape proved to be as effective obstacles to an advancing army as any fortifications.

The battles of Dien Bien Phu (1954) and Khe Sanh (1968) possessed siege-like characteristics. In both cases, the Vietcong were able to cut off the opposing army by capturing the surrounding rugged terrain. At Dien Bien Phu, the French were unable to use air power to overcome the siege and were defeated. But at Khe Sanh a mere 14 years later, advances in air power allowed the United States to overcome the siege and win the battle.

A booby trap is distinguished from a land mine by the fact that it is an improvised weapon, perhaps made from an artillery shell, or a grenade, or a quantity of high explosives, whereas a land mine is manufactured for its specific purpose. A booby trap may be buried in the manner common with land mines, or not, though as a rule it is concealed in some fashion, and set to be detonated by means of pressure or a trip wire. During World War II retreating British and Canadian soldiers in France in 1940 made booby traps from artillery and mortar shells, burying them in roads behind them as they retreated, or hanging them from trees concealed by the leaves and rigged with tripwires concealed in the grass around the tree.

During the Vietnam War, motorcycles were rigged with explosives and abandoned. Soldiers would be tempted to ride the motorcycle and thus trigger the explosives. As well, Viet Cong soldiers would rig Rubber Band Grenades and place them in huts that Americans would likely torch. Another popular booby trap is the Grenade in a Can trap. This involves a primed grenade in a container and a string attached, sometimes with the grenade's fuse mechanism modified to give a much shorter delay than the four to seven seconds typical with grenade fuses. The Viet Cong soldiers primarily used these on doors and attached them to tripwires on jungle paths.

During the Al-Aqsa Intifada, Palestinian fighters used booby traps widely. The largest use of booby traps was in Jenin during Operation Defensive Shield where a large number of explosive devices were planted.