Van Statten Incident
The Battle of GeoComTex started when the "last" Dalek escaped the Vault in 2012, at the GeoComTex base.
Two hundred security personnel fought the Dalek, but all were exterminated without even scratching it. The Dalek kept travelling through the base, up a staircase and even turned on the sprinklers to make the humans' guns short-circuit. The Dalek eventually found Henry van Statten and nearly killed him.
The Dalek had absorbed Rose Tyler's DNA to regenerate itself and escape. A side effect of this was that it has been contaminated with emotions. The Doctor was about to blow it up with some alien weaponry, but was convinced otherwise.
The Dalek ended its pain by self-destructing. The base was sealed off, and Henry van Statten's memory was erased. (DW: Dalek)
