War against mankind (The Sea Devils)

The Master once awoke a colony of Sea Devils and manipulated them into launching a"war against mankind" to reconquer Earth. (TV: The Sea Devils)

Chronology
The Third Doctor experienced this war during his exile on Earth. (TV: The Sea Devils)

The Fourth Doctor later found himself at this event again while travelling alone. (COMIC: Under Pressure)

Dating
The Twelfth Doctor recalled that this took place in either 1972 or 1982. (COMIC: Clara Oswald and the School of Death)

History
A group of Sea Devils hibernating beneath the English Channel were awoken by the Master. He attempted to persuade them to reclaim the planet from the human race. Despite the Third Doctor's efforts to convince them otherwise, hostilities escalated when Private Secretary Walker ordered the Royal Navy to attack the base, and the Sea Devils decided to go to war with the humans. However, before they could use the Master's sonar device to reactivate more bases, the Doctor blew up their base by overloading the devices by reversing the polarity of the neutron flow, preventing the war between humans and Sea Devils from starting. (TV: The Sea Devils)

Aftermath
The Third Doctor met the Eighth Doctor shortly after this event, while trying to recapture the Master. (PROSE: The Eight Doctors)