War

War is any large scale, violent conflict. By extension, the word can be used for any struggle. A group of combatants and their support is called an army on land, a navy at sea or in space, and air force in the air. Wars may be prosecuted simultaneously in one or more different theaters. Within each theater, there may be one or more consecutive military campaigns. A military campaign includes not only fighting but also intelligence, troop movements, supplies, propaganda, and other components. Continuous conflict is traditionally called a battle, although this terminology is not always applied to conflicts involving aircraft, missiles or bombs alone, in the absence of ground troops or naval forces.

There are many wars in and related to the Halo universe.

Forerunner wars

 * Forerunner-Human War - (~110,000 years ago)
 * Forerunner-Flood War - (~100,000 years ago)

Covenant wars

 * San 'Shyuum Civil War - (Age of Conflict)
 * Sangheili-San 'Shyuum War - (Age of Conflict)
 * Taming of the Hunters - (Age of Doubt)
 * Unggoy Rebellion - (Age of Conflict)
 * Human-Covenant War - (Age of Doubt to Age of Reclamation)
 * Great Schism - (Age of Reclamation)

Human wars

 * Forerunner-Human War - (c. 110,000 B.C.E.)
 * World War II - (1939 to 1945)
 * Interplanetary War - (2160 to 2170)
 * Jovian Moons Campaign - (2160)
 * Rain Forest Wars - (2162)
 * Argyre Planitia Campaign - (2163)
 * Inner Colony Wars - (2400s)
 * Insurrection - (2494- 2537)
 * Operation: TREBUCHET - (2511 to 2524)
 * Harvest Insurrection - (2524)
 * Insurrection of Mamore - (2537)
 * Human-Covenant War - (2525 to 2553)