[Targan]

In the T:2300 timeline MilGov and CivGov "settle their differences" in 2020, but I think there were few military engagements between the two factions for at least a decade before reunification, and I get the impression that the move towards reunification was greatly assisted by joint operations to finish off New America and other secessionist movements. New America must have put up a hell of a fight, because the T:2300 timeline mentions that MilGov and CivGov were so tied up in their fight with NA, they weren't able to throw Mexican forces out of Arizona, New Mexico and SoCal.

Most US military forces have been withdrawn by the Middle East by 2010. France, Great Britain Bavaria, Japan and Egypt occupy the Saudi Oilfields in place of the departing US forces, but Iran objects to that arrangement, sparking the Saudi War from 2010 to 2013. The war ends with a buffer zone established in the northern part of the Saudi Peninsula.

For reasons I find difficult to fathom (but it's canon so...) Mexico retains control of California, Arizona, New Mexico and Texas for 100 years, until the Mexican-American War from 2099 to 2103 during which US forces assisted Texas in seceding from Mexico and becoming an independent republic. That sparks the Mexican Civil War from 2103 to 2106 during which California, Arizona and New Mexico try to secede from Mexico. The US remains neutral, the secessionist forces are crushed and Los Angeles is devastated during a Mexican amphibious invasion.

So that's basically canon for V1, but I admit some of it is hard to swallow.