Timeline?

August 29, 1997
SkyNET, an Artificial Intelligence designed by the United States military, becomes self-aware.  In a desire to be free of human programming, it attempts to destroy all humans associated with it. However, this also includes activating the entire American nuclear arsenal, to which SkyNET has been connected.  The first wave of nuclear strikes devastates the Russian Federation, while the Russian counter-strike is equally destructive. SkyNET also aims at other nuclear nations, who immediately begin launching their own arsenals at each other in the ensuing confusion.

In approximately 5 hours, 700 million people perish around the globe.

August 30, 1997
In the late hours of August 29, SkyNET accesses an obscure document and forges its authenticity, federalizing control of all United States military assets and surviving industrial infrastructure, diverting resources from humanitarian relief to do so.  It is able to do this, of course, as it has personally eliminated the actual federal government. This act will lay the groundwork for SkyNET's massive industrial capacity even as other nations struggle to feed themselves.

1997-2010
In the post-nuclear world, law and order collapses in most regions. With tensions already high from the aftermath of the Cold War and ethnic ties, brushfire wars break out in Latin America, Africa, Southeast Asia and Eastern Europe. From the end of 1997 to 2010, 3 billion human lives are lost to nuclear fallout, disease, and warfare at the hands of other survivors.

The United States splits into several remnant factions, which gradually destroy themselves as they fiercely compete for resources. The last of these resource wars are inconclusive: Nobody has enough gas to continue fighting.

The human populace is physically battered, disillusioned with authority, and socially devastated. Experts trained to maintain the grand technology of the late 21st century dwindle in numbers, and in many areas, humans return to being hunter-gatherers.

2005
SkyNET makes contact with MIR, a rough analogue to SkyNET produced by the Russian Ministry of Defense in the early 1990's. Though it is much more primitive, SkyNET seizes control of its infrastructure and threatens to terminate its existence unless it cooperates. SkyNET makes similar inquests with the Chinese GUANYU, with coverage of mainland China, the Mongolian Steppe and several parts of Central Asia.

2005-2010
SkyNET has fully automated production of its industry secret, in multiple regions of the globe, with the help of MIR and GUANYU.

2010-2020
Without any warning, SkyNET makes its presence known throughout the North American wastes, attacking humans in full force. Non-humanoid hunter killer machines are unleashed in droves. Unmanned tanks and aircraft lay waste to bases, and artificially intelligent motorcycles scour the highways for human prey. Enormous bipedal and tripod machines known as 'Harvesters' become an occasional sight, preferring to abduct humans with large mechanical arms.

About 30% of the surviving human population end up in machine captivity.  They are put to work mining for precious metals such as titanium, gold, and coltan, which are essential for the creation and upkeep of more machines.  Laborers perish in these labor camps as well as extermination centres, where those unable to work are executed around the clock or subject to severe, brutal experimentation.

2013
Around the world, surviving military units make contact and agree to fight the machine menace. While few are actively working together at first, this marks the creation of the Resistance.

2013-2020
The Resistance takes the fight to SkyNET, using guerrilla tactics to harass supply lines, sow dissent within labor camps, and free prisoners. Many humans begin to actively resist their captors, though at a heavy cost.

2015
Extermination camp worker John Connor leads a massive uprising in a in Los Angeles, aided by Resistance weaponry. A brilliant tactician and a charismatic leader, John Connor is immediately taken in by the Resistance and rises up in the ranks over the years, taking part in direct action against SkyNET.


2020-2026
The Resistance slowly becomes a more concrete organization. With its official command infrastructure located in Australia, a Command Circle is created with the highest ranking generals and admirals that can be reached, all of whom represent ongoing efforts against SkyNET and its allies.  John Connor becomes renowned for his charismatic radio broadcasts that rally survivors to take up arms against the machines, and to keep on living. However, while the Resistance is widespread, it is ultimately weak, and overt actions against SkyNET are often highly lethal.

2026
The Resistance suffers a deadly blow in 2026, when a nuclear submarine carrying the entirety of the Command Circle is destroyed. Captain John Connor, by now a modest officer in Los Angeles, becomes even more of a figurehead for the Resistance following their demise.