Sea Base 4 incident

The Sea Base 4 incident was the name given by The Secret Lives of Monsters to the event in which Sea Base 4 was attacked by the Silurians and the Sea Devils in 2084. (TV: Warriors of the Deep, PROSE: The Secret Lives of Monsters)

Aftermath
Shortly after, a Breaking News tweet reported "Minister for Peace says world war is now 'inevitable' following discovery of wrecked Sea Base 'full of corpses'."(PROSE: When It Was Fun)

Behind the scenes

 * A Sourcebook for Field Agents states that the Doctor reported this incident, which he claimed also involved the Master, to the Time Lords, who understood that the war had successfully been averted at the cost of the last known group of Silurians and Sea Devils.