First Battle of the Masurian Lakes

First Battle of the Masurian Lakes
	Part of the Eastern Front of World War I
	; Eastern Front to 26 September 1914.
Date	2–16 September 1914
Location	East Prussia, Germany (present-day Russia and Poland)
Result	German victory
Belligerents
Germany	Russian Empire
Commanders and leaders
Paul von Hindenburg; Erich Ludendorff; August von Mackensen	Paul von Rennenkampf
Units involved
8th Army	1st Army; 10th Army
Strength
Total 244,391 men; 7 military corps; 1,146 guns; 400 machine guns	Total 150,000 to 210,000; 724 guns; 4 corps and one division.
Casualties and losses
(1 - 30.09.1914):; 1,555 killed; 10,412 wounded; 1,552 missing; Total 13,515; Lost: ; 17 guns ; 17 machine guns 10,000 killed, wounded and missing; Other Estimate:; 40,000 killed and wounded	100,000–125,000 killed, wounded and captured,; Lost: ; 162 guns ; 174 machine guns Russian Estimate:; about 60,000 died, wounded and prisoners; German data: 100,000 men, including 45,000 prisoners

The First Battle of the Masurian Lakes was a German offensive in the Eastern Front 2–16 September 1914, during the Russian invasion of East Prussia. It took place only days after the Battle of Tannenberg where the German Eighth Army encircled and destroyed the Russian Second Army. Using the rapid movements aided by the East Prussian railway network, the Eighth Army reformed in front of the spread-out Russian First Army and pushed them back across their entire front, eventually ejecting it from Germany. Further progress was hampered by the arrival of the Russian Tenth Army on the Germans' right flank.

By the conclusion of the battle, the Imperial German Army had destroyed the Second Army and shattered the First in a series of actions over only a few weeks. However, Russia had the largest army in the world, so the Russian army very quickly restored its losses in manpower, and after a couple of weeks the Russians launched a new offensive in East Prussia.