C-Day
From Tardis Wiki, the free Doctor Who reference
C-Day or Computer Day was to be the day all the world's computers would be networked together and placed under the control of WOTAN.
History
Initially set for Monday, 16 July 1966, C-Day was cancelled when the WOTAN computer was destroyed after failing to take over London. (TV: The War Machines, PROSE: Who Killed Kennedy)
Torchwood was involved in the clean-up operation for C-Day. (AUDIO: The Law Machines) UNIT was embarrassed not to be involved "during the whole thing with the Post Office Towers", as the organisation was not founded until 1967. (TV: Survivors of the Flux)