Inner Colonies

The Inner Colonies were the first worlds terraformed and colonized by the UN, relieving the overpopulation pressure on Earth that resulted in the Interplanetary War.

The Inner Colonies consisted of the 210 planets which were colonized before 2390. In 2490, Reach, which was located near the boundary of the Inner and Outer Colonies, became the UNSC's military center. As the UNSC began settling the Outer Colonies, the Inner Colonies, with their established social and economic infrastructures, became the political and economic basis of the UNSC, supplied with raw materials from the newer settlements.

Numerous ships were pulled from their positions in the Outer Colonies to defend the Inner Colonies. Old ships, such as the Halcyon-class Cruiser, were refitted and brought back into service to supplement the remaining defense forces. At the beginning of the Battle of Reach, dozens of Inner Colony planets were bypassed by the Covenant Fleet attacking Reach, so it can be presumed that a number of those Colonies survived, considering the next Covenant attack was Earth.

The Inner Colony Wars
It is known that there was a war some time before the 26th century called the "Inner Colony Wars". Very little is known about it and it might just be an alternate name of the Interplanetary Wars, though the name would be of a post-Outer Colonies age, and probably only referring to the Sol system colonies.

Known Inner Colonies
Epsilon Eridani system Sol system Ectanus 45 system Skopje - Glassed by the Covenant in 2547.
 * Reach - Glassed by the Covenant in 2552.
 * Circumstance - Unknown status.
 * Tribute - Glassed by the Covenant in 2552.
 * Beta Gabriel - Unknown status, likely to have been glassed by the Covenant.
 * Earth - Controlled under UNSC.
 * Mars - Unknown status, most likely to have survived.
 * Jupiter - Unknown status, most likely to have survived.
 * Pluto - Controlled under UNSC.
 * Chi Rho - Unknown status.