A TARDIS cradle facility was established by Gallifreyan during the War. They were located partially within the Vortex and dimensionally transcendental. They held and force grew War TARDISes. When Compassion entered one of the cradles, she communicated with a group of War TARDISes. They expressed sheer rage at the control imposed by the Gallifreyans. This rage, directed at the cradles, caused dimensional fluctuations and eventually lead to them breaking. (PROSE: The Taking of Planet 5)