The art of planning major military movements is called strategy. Tactics is the execution of those plans on the battlefield. Logistics deals with transporting troops to fighting fronts and supplying them with guns, ammunition, food, and clothing. These three terms cover virtually the whole range of military affairs.

This term has often been defined as "the art of the general," but in modern war it is also the concern of a country's political leaders. Grand strategy is the overall planning of a war, involving naval and air forces as well as armies. The strategist decides where to place his forces, when to attack, and when to go on the defensive. His role is somewhat like that of a football coach who trains his team to use certain plays and decides how and when to use his best players.

If strategy is compared to the work of a football coach, tactics may be likened to the work of a quarterback who calls the signals on the playing field. The tactical commander tries to surprise, outwit, and outmaneuver the enemy.

On the battlefield, the tactical commander usually sends out scouting parties to discover where the enemy is, how strong he is, and how well defended his positions are. The commander also makes use of aerial photographs obtained from satellites, reconnaissance airplanes, and drones (unmanned aircraft). With knowledge thus collected, he can choose the best time and place for his attack.

In making an attack, army commanders usually follow one of three standard patterns—penetration, flank attack, or encirclement (sometimes called envelopment). Penetration is a plunge through the enemy's line. Such an attack is often spearheaded by a hard-hitting tank and infantry team. The flanks, or ends, of an enemy's line are usually weaker than the front, and a flank attack is an attempt to take advantage of this weakness. In an encirclement the aim is to surround the enemy force. Sometimes troops parachute behind enemy lines, or are landed from helicopters, to seize key points and help open the way for ground attackers.

In guerrilla warfare, as in the Vietnamese War, these traditional methods are generally impractical because guerrillas do not form lines of battle but use hit-and-run tactics.

Tanks, mobile artillery, trucks, aircraft, and missiles are extremely valuable in all forms of attack. An army is usually at a great advantage if it can move quickly, strike the enemy by surprise at a weak point, and bring up reinforcements as soon as they are needed. The military term for this is mobility. But mobility must be coupled with firepower—powerful, accurate, rapid-firing guns and missile launchers in sufficient numbers to outgun the enemy—if an army is to be truly effective.

Most military offensives are preceded by intensive artillery and missile barrages aimed at knocking out the enemy's strong points and destroying bridges and railways in his rear. Aerial bombing and strafing attacks supplement artillery fire.

On the defensive, armies conceal their positions by camouflage, and "dig in" for protection. When time is short, troops dig simple foxholes for shelter. If there is more time, elaborate bunkers may be built of heavy logs or concrete and systems of trenches may be dug. Barbed wire and land mines help block the enemy's approaches.

This branch of military science is discussed in the article Logistics.