World War VI was a conflict that began in the year 5000, when the Supreme Alliance used the Peking Homunculus to assassinate the Commissioner of the Icelandic Alliance. (DW: The Talons of Weng-Chiang)
The Peking Homunculus was created by Magnus Greel in Peking. It was sent as a gift to the Commissioner of the Icelandic Alliance. Though it was believed to be a toy for his children, it was actually an assassin and killed the Commissioner and his family. This sparked off a war between the Icelandic Alliance and the Supreme Alliance.
For a while, the Supreme Alliance prospered, but the war turned against them in the final battle for Reykjavik between the Alliance and the Philippines. The Doctor marched with the Filipino Army in their advance and witnessed their victory. After the conflict, Magnus Greel took the Peking Homunculus and escaped to 19th century China using an experimental time cabinet created by Dr. Findecker. (DWN: Doctor Who and the Talons of Weng-Chiang)