Battle of Poseidon
From Tardis Wiki, the free Doctor Who reference
The Dalek Survival Guide acknowledged a claim that, during the Battle of Poseidon, several Dalek battalions were wiped out by their own Daleks, necessitating the introduction of bumpers to the Dalek casing which could detect signals that warned when other Daleks were dangerously close. However, since there was no visual evidence of Daleks ever being without these fenders, this claim was treated with a degree of skepticism. (PROSE: Dalek Survival Guide)
