In a repeat of the Battle of Mukden, Paul von Rennenkampf failed to assist the losing commander at this battle.
Shortly before this battle, a previous failure at Gumbinnen and an ill-advised suggestion to retreat led to the dismissal of Maximilian von Prittwitz from his command post. In a repeat of the Battle of Mukden, Paul von Rennenkampf failed to assist the losing commander at this battle. This battle's name was coined by Max Hoffmann, who was responsible for the winning strategy of (*) encirclement during it. This battle was followed by a clash at the Masurian Lakes. Unencrypted radio signals enabled this battle's winning side to track the troop movements of Alexander Samsonov, who shot himself instead of reporting his casualties to Nicholas II. For 10 points, name this massive 1914 victory for Erich Ludendorff and Paul von Hindenburg at the site of the 1410 Battle of Grunwald
Shortly before this battle, a previous failure at Gumbinnen and an ill-advised suggestion to retreat led to the dismissal of Maximilian von Prittwitz from his command post.
Second Battle of Tannenberg [do not accept: "First Battle of Tannenberg" or "Battle of Grunwald"]