Things already seem to be just a little bit too big in scope and scale for The Doctor to handle during the first three episodes of The War Games. There is an epic feel to proceedings never seen up to this point in the programme's history. And then things ramp up considerably with about three minutes left in the episode.
The moment where The Doctor (who has conveniently lifted his visor to allow for his face to be visible) and the War Chief recognize each other is one of the most chilling and exhilarating scenes in Doctor Who history. The sheer look of terror in The Doctor's eyes is remarkable; there is clearly a past between the two characters. A past that The Doctor has no wish to revisit. The scene also adds much to the mystery of the War Chief and his history with The Doctor. How do they know each other? Why does it appear that The Doctor fears the War Chief so much? Of course, for those who have seen the story as a whole know the answer by now, but for viewers who first saw this episode air in the spring of 1969, it must have triggered a thousand questions about their hero, The Doctor, with an unknown past.
We also see the inside of one of the capsules that are seen to load and unload squadrons of soldiers in the various different time zones. Surprise - it's bigger on the inside than on the outside! The Doctor reacts at this as if he's something like this before. Could he be referring to the Daleks' dimensionally transcendental time machine as seen in The Chase? (No, we know he's not...)