Board Thread:The Reference Desk/@comment-24894325-20171006064843/@comment-1432718-20191103012938

From Ante Bellum:

Ace and the Doctor arrive in Constantinople on 8 June 1914. The Doctor says (at different times in the story) that Gavrilo Princip is planning an assassination, and that WWI will start in August.

Not super helpful, but at least it's progress.