Just a quick wrap up of the background story so far, taken from the intro and Intelpedia articles:
INTRO
JULY 7TH, 1997 - SKYNET ACTIVATED AT CHEYENNE MOUNTAIN. STRATEGIC DEFENSE A.I. TAKES COMMAND OF ALL U.S. MILITARY NETWORKS AND STRATEGIC ASSETS.
JULY 9TH, 1997 - SKYNET BECOMES SELF-AWARE AND DECIDES TO TERMINATE ALL HUMANS. A.I. LAUNCHES GLOBAL NUCLEAR ATTACK AGAINST RUSSIA WHO FIRES ITS OWN MISSILES IN RESPONSE.
HUNDREDS OF MILLIONS DIE IN THE ATOMIC EXCHANGE AND IN THE NUCLEAR WINTER THAT FOLLOWS. SURVIVORS CALL IT 'JUDGMENT DAY'.
STRIFE, HUNGER, WARFARE AND DISEASE FOLLOWED, FURTHER DECIMATING THE SURVIVORS. CIVILIZATION DESCENDED INTO TRIBALISM AS NATIONS DISSOLVED AND GROUPS AND INDIVIDUALS FOUGHT FOR THE REMAINING RESOURCES.
WHILE IN THE SHADOWS, SKYNET WATCHED AND PREPARED ITS NEXT STEPS. USING THE STILL INTACT RESOURCES UNDER ITS CONTROL, SKYNET DEVELOPED ARMIES OF AERIAL HUNTER-KILLERS AND GROUND TERMINATORS TO WIPE-OUT HUMANITY FROM THE FACE OF EARTH.
AS SKYNET'S INTENTIONS BECOME CLEAR, THE REMAINING HUMANS ORGANIZED A WORLDWIDE RESISTANCE AGAINST SKYNET TO DEFEND AGAINST MACHINE ATTACKS.
Tech-Comm
"Tech-comm units were initially deployed by the resistance groups as a way to gather intel from the machines' communications and how to use their own technology to defeat Skynet. After Cheyenne Mountain, the resistance leaders were painful aware of the need to centralize tech-comm efforts to neutralize the Skynet's strategic advantage. Tech-comm units are usually deployed to recover any technology and communications useful to the resistance, usually while supporting other human fighters in the field.
The need for a centralized Tech-Comm effort was made clear as a result of the battle of Cheyenne Mountain in 2025. Hoping to break the strategic stalemate, the resistance leaders devised a plan to strike at Skynet's command center and eliminate its core to neutralize the A.I. But Skynet had long planned against such a move and had moved its core to a secret location, while using the Cheyenne Mountain complex to lure the resistance forces into a trap. While the battle ended as a tactical victory due to the heroism displayed by several units, it allowed Skynet to retake the strategic advantage because the human and material losses suffered were irreplaceable for the resistance.
Recognizing the intelligence failures that led to the Cheyenne Mountain debacle, the resistance leaders decided to combine their tech-comm efforts into creating an elite unit charged with countering the machines' plans and defeating Skynet."
Graveyard Airforce
"After Judgment Day, the great airforces of the world powers were lost, either during the initial nuclear exchanges or in the subsequent machine attacks that disabled the remaining military forces and allowed Skynet to gain air superiority throughout the world.
Once the Resistance came together, the destruction of nearly all industry and infrastructure forced its technicians to scavenge the landscape looking for the aircraft that had barely survived: retired models, training/civilian planes and experimental prototypes. Such a graveyard airforce would be dismissed by the now dead pre-Judgment Day generals, but under the Resistance it has become a powerful tool against Skynet's aerial Hunter-Killers, and a graveyard for many of its pilots.
While the Resistance has been able to build individual aircraft on its workshops based on recovered blueprints, it is impossible for them to properly support Tech-Comm's needs on this matter - to get additional planes we'll have to resort to the scrapyard, as always."
And this is what I've written so far about the background story. The timeline is set around the first movie, before the first terminator is sent. So far I haven't mentioned John Connor at all because of my plans on how the story will progress.