A conflict fought across time between factions controlled by agents from the future.
The Temporal Cold War was a conflict among factions from the future who tried to alter history to their own advantage. Captain Archer and the crew of Enterprise were drawn into it from their first mission in 2151, when the Suliban Cabal attacked them while trying to stop the Klingon courier Klaang from delivering information to his government.
The Cabal, including its operative Silik, received orders and genetic enhancements from a mysterious figure from the future. Opposing them was Crewman Daniels, an agent from the thirty-first century who served aboard Enterprise for a time and sometimes took Archer into the future. The Sphere Builders behind the Xindi attack on Earth were also said to be part of the wider conflict.
In the fourth-season story Storm Front, Archer stopped an alien faction led by Vosk that had changed history to create a Nazi-occupied America, and Daniels told him the war was over. In Discovery, set in the thirty-second century, the Temporal Wars that followed had led to the Temporal Accords banning time travel.