This chapter focuses on three events to demonstrate some larger military developments on the Eastern Front. It also explains why they were turning points of First World-War and how they influenced its duration and outcome. The encounters presented in the chapter are the Battle of Tannenberg, the fall of Przemyśl and the Battle of Gorlice-Tarnów, and the Brusilov offensive. The victory of Tannenberg gave Germany time to organise its defence in the East, and indeed during the rest of the war Russian-forces were unable to defeat German-troops in a major battle. The surrender of Przemyśl could easily have been a Stalingrad of the First World War. The logic of Gorlice-Tarnów offensive was closely connected with the Austrian defeat at Przemyśl. The prominent feature of Brusilov attack hit the Austrian lines on a large-sector of the front, and quickly became a major success.