Battle group

A battle group, sometimes rendered as battlegroup, is an organization of ships that is generally smaller than a fleet. Battle groups are usually created on a temporary basis, with a specific mission or to accomplish a specific task. The term applies to both UNSC and Covenant naval groups.

UNSC
Battle groups are usually commanded by an admiral, though there have been instances of smaller battle groups being led by captains. Each battle group is assigned a number or a code name. A UNSC battle group whose flagship is a carrier is referred to as a carrier group. By 2552, all UNSC battle groups had a prowler assigned to their ranks, to provide electronic intelligence and to gain an advantage over the enemy by laying minefields.

Known UNSC battle groups

 * 4
 * 6
 * D
 * Dakota
 * India
 * Leviathan
 * Sierra-3
 * Sol Defense Group 3/A-5
 * Omicron
 * Tango
 * X-Ray

Covenant
Although the Covenant organize smaller fleet units on a temporary basis similar to UNSC battle groups, their naval doctrine identifies such units as fleets rather than battle groups; for example, the Fleet of Sacred Consecration was still identified as a fleet despite only consisting of 15 ships. Instead, the term "battle group" is applied to certain tactical formations of Covenant ships that are part of a larger fleet; for example, the Fleet of Particular Justice had several "CCS-class battle groups", each consisting of three s. Similar to the naming of their ships and fleets, the Covenant themselves often derived the naming of their battle groups from their religious nomenclature.

Trivia
The funding of the SPARTAN-II program, including their MJOLNIR armor and training, cost about as much as a battle group.