Board Thread:The Panopticon/@comment-6032121-20190202144408/@comment-5918438-20190202234838

Basically, The War Master is Jacobi's incarnation before he turned himself into a human. This is the same incarnation of the Master before he becomes Professor Yana. At the end of the first box set, the Master uses the Chameleon Arch and turns himself into a human baby, as referenced by Yana in Utopia. Other box sets are set earlier on in the Time War. Hope that helps.