The Russian Army had now fully mobilised, a lot earlier than Germany had expected. Now half their army was trapped in trenches in France whilst the other half dealt with the Russians. The Russian troops made an advance into Prussia but were swiftly crushed at Tannenberg, where 90,000 Russian troops were taken prisoner and an entire army was wiped out. Another victory at Masurian Lakes forces the Russians out of the region.
Further south, the conflict between Austria-Hungary and Serbia was going bad for Austria-Hungary due to a humiliating loss at the Battle of Cer. An offensive against Russia also fails and the Austro-Hungarians are pushed back, with a siege on Przemysl beginning not long after. The Germans, in an effort to distract the Russian forces, engaged in a series of battles at Lodz in modern day Poland.
Eventually, the Ottoman Empire, a large Middle Eastern Empire spanning Turkey, Jordan, Palestine, Syria, Lebanon, Iraq, and parts of Saudi Arabia, join the fighting on the side of Germany and Austria-Hungary, by sending some ships into the Black Sea, launching naval bombardments on the naval bases of Odessa and Sevastopol, while engaging with ground units on the Georgian border. Due to the vast length and low density of the line, trench warfare never set in like it did on the western front.