It was intercontinental alliances that caused WW1. It began when Austria-Hungary declared war on Serbia, causing Russia to jump in and defend Serbia. Germany then declared war on Russia to protect their allies, which prompted France to jump in and defend Russia. When Germany attacked France via Belgium, Britain entered. Eventually Japan, Italy and the US also jumped in, but the conflict was well underway at this point.
Related: the best WW2 games on PC.
Looking at the catalyst, it's quite clear that Russia and France were two of the main combatants, but they're being held back as DLC for Battlefield 1 that you'll either need to get via the Premium Pass or presumably buy separately. For some reason, this isn't the case for the US and Britain.
There are also 16 multiplayer maps, 20 new weapons, Battlepacks and some other gubbins. Here's everything you get in the $50 expansion pass:
- 4 upcoming digital expansion packs, including:
- Two-week early access to each expansion pack
- Play as new armies including France in Battlefield 1 They Shall Not Pass, and the Russian Empire in an upcoming expansion pack
- 16 new multiplayer maps
- New Operations and game modes for more ways to play
- New Elite classes
- 20 new weapons
- New vehicles
- 14 Battlefield 1 Battlepacks containing stand-out weapon skins, delivered monthly from November 2016
- 14 unique dog tags distributed over the course of the Battlefield 1 Premium Pass period
The first expansion, They Shall Not Pass, is released in March, so you've got plenty of time to decide before dropping almost the price of a full game on its extras.
Battlefield 1's open beta begins August 31.