Dalek Wars

The "Dalek Wars" were the series of conflicts that involved forces of the universe, primarily humans, battling the Daleks. These included the Human-Draconian War in 2520, the Second Dalek War, (TV: Frontier in Space, Planet of the Daleks) and the Third Dalek War which took place prior to Steven Taylor's time. These conflicts put a stop to Earth's expansionist era. (PROSE: The Chase)

A Velyshaan museum contained an exhibit on the wars. (PROSE: Museum Peace) By the far future, they were considered a part of the First Segment of Time. (TV: The Ark)

Behind the scenes
Under the reasoning that a Second and Third Dalek War occurred, it is implied that a First Dalek War also occurred, but none has been explicitly mentioned by name. Multiple Dalek attacks had been made on Earth prior to this era most notoriously the decade long occupation from 2157 (TV: The Dalek Invasion of Earth), and any of these may have been considered the First Dalek war.