2540

In 2540, the Third Doctor and Jo Grant prevented from fomenting war between the Earth Empire and the Draconian Empire. (TV: Frontier in Space, PROSE: Doctor Who and the Space War)

They defeated the Daleks' invasion plans on Spiridon. (TV: Planet of the Daleks) However, the path to the Second Dalek War was already set.

On 21 June, Bernice Summerfield was born on Earth colony Beta Caprisis. (PROSE: Just War, The Doomsday Manuscript, The Judgement of Solomon)

Within 2540 alone, entire planets died in the fire of war that swept through the entire galaxy. Colony worlds of a billion people were destroyed in an hour of atomic bombardment with fleets of ships wiped out. Genocidal policies on all sides had wiped out a dozen alien species, leaving nothing but ruins. (PROSE: Beige Planet Mars)

Behind the scenes
22.09.72.2540 is given as the time the Earth cargo ship C982 jumps into hyperspace at the beginning of the television story Frontier in Space and the Doctor tells Jo Grant that they are in the 26th century. 2540 is explicitly cited as the year in the novelisation and the novel Shadowmind. The telelvision story Planet of the Daleks follows some time close to this point.

The novel Just War indicates that 25th century dates given in previous books for Bernice Summerfield's life were actually part of one of the other calendar systems in use in the Mutter's Spiral of her time. In another system, she was born in 2422. (PROSE: Falls the Shadow)