The time war

The  Time War was the war between the Time Lords and the Daleks the war that it lasted for 400 years and would destroy many planets and civilisations

At the heart of the war, Dalek forces numbered in the billions and fielded a fleet of ten million flying saucers. The Time Lords used over a million Battle TARDISes that were destroyed in the proses.

It resulted in the apparent destruction of Gallifrey, leaving only few Time Lords( including The Doctor' the Master'Jemma'The rani and the Monk) left in the universe and a small number of Daleks as survivors.