Planet (The Doctor Strikes Back)

An Earth-like planet was home to a Dalek outpost, as it was rich in the materials they needed to construct more Daleks. In 2135, the Second Doctor arrived on the planet, intent on fighting the Daleks' power. Using a home-made Dalek casing for a disguise, he infiltrated the outpost (leaving John and Gillian in the TARDIS) and learned that the Dalek Supreme was on his way to supervise the production of thousands of Daleks. He went to the mine to sabotage it, but was spotted leaving his casing and forced to flee. The Daleks searched for him and, unable to tell which one was the imposter, began destroying each other. The Dalek Supreme contacted them from his ship and ordered them to stop, but the Doctor then impersonated the Dalek Supreme and ordered the Daleks to destroy themselves. The Doctor escaped in the TARDIS just before the Dalek Supreme arrived, having struck a devastating blow against the Daleks. (COMIC: The Doctor Strikes Back)