A video introduction for the mode coming with They Shall Not Pass was shared.
As you surely know, Battlefield 1 is getting a whole set of expansions thanks to the Premium Pass (DLC will be available separately, if you wish). The first of them is They Shall Not Pass, which should release soon.
The upcoming DLC will include the Frontlines mode. It’s a symmetrical combination of Conquest and Rush modes. At the start of each match both factions will have to fight for the middle point and then storm a zone hold by the enemy. If successful, two telegraph points in the base must be captured.
You can get a better look at the mode in the recently released video: