World War V was an Earth conflict in which the Doctor was present. (TV: The Unquiet Dead, AUDIO: Singularity, The Gathering)
According to one account, the war was fought in the 49th century. (AUDIO: Singularity) According to another account, in the 37th century, the war was described by Cazkelf as "Earth's recent history". (COMIC: Art Attack)
During the conflict, much of Earth's art treasures were destroyed, though these did not include the Mona Lisa. (COMIC: Art Attack)
On 24 December 1869, the Ninth Doctor mentioned that he had seen the war along with the fall of Troy and the Boston Tea Party when he thought he might meet his end in a dismal Cardiff dungeon at the hands of the Gelth. (TV: The Unquiet Dead)
In the late 21st century, the Fifth Doctor once rebuked Qel for the failure of the Somnus Foundation's museum of future history to even mention the conflict in its entry on the 49th century. (AUDIO: Singularity)
It was followed by World War VI in 5000. (TV: The Talons of Weng-Chiang, PROSE: Doctor Who and the Talons of Weng-Chiang, AUDIO: The Butcher of Brisbane)