10 Doctor Who Moments Deeper Than You Think
3. The Destruction Of The Zygon Homeworld
In 1975's Terror of the Zygons, the titular alien species sought a new home after their own planet had been destroyed, with 2013's The Day of the Doctor - the first episode of the modern series to feature the Zygons - revealing that said homeworld was destroyed during the early days of the Time War.
This isn't a surprise, as many species (including the Gelth) lost their homes during the great war between the Daleks and the Time Lords. However, what makes the Zygons' case interesting is that reference to the early days of the Time War.
Russell T Davies previously stated that the Time War began when the Fourth Doctor was sent to avert the creation of the Daleks. This classic Tom Baker serial - Genesis of the Daleks - concluded in April 1975.
Four months after the Time Lords fired this first shot of the Time War, and the Zygons were seeking a new home. That's because Terror of the Zygons aired in August 1975 - it doesn't get more early days of the Time War than that!