Slitherine

Tried SL as Entente for first time. Paris held okay and offensive stopped. All seemed to be going well in the East, Warsaw held etc, Russians had high morale and 1 or 2 collapse points. The Tsar was in command when suddenly in late 1915 (or possibly early 1916) the Russians surrendered without warning or apparent reason.

This came at as shock but actually kept the challenge up on what was becoming a one sided game.

What might cause such a surrender?