http://www.pcgamer.com/battlefield-1-in-the-name-of-the-tsar-release-date-confirmed/

Battlefield 1's second major expansion, In the Name of the Tsar, promises six new maps, the Russian army, and the Women's Battalion of Death. As such it's billed as the "most extensive Battlefield expansion yet", and now has a launch date: September 19.

First teased at E3 earlier this year, we now know that the add-on also brings with it 11 new weapons, a handful of new vehicles, the Hussars and a new 'Supply Drop' mode, among other things detailed here.