Winter Battle in Masuria — Russia Suffers 200,000 Casualties

Germany launched a winter offensive in Masuria, temporarily surrounding the Russian Tenth Army in the Augustów Forest. Russia lost approximately 200,000 men including 90,000 prisoners in brutal winter conditions. The battle demonstrated Russia's vulnerability on the Eastern Front and foreshadowed the catastrophic Great Retreat later that year. The Russian officer corps was devastated; General Sievers was relieved of command.