First Battle of The Masurian Lakes - Battle

Battle

German efforts at mopping up the remains of the Second Army were essentially complete by 2 September and Paul von Hindenburg immediately started moving his units to meet the southern end of Rennenkampf's line. He was able to safely ignore the Russian right (in the north), which was in front of the extensive defensive works outside of Königsberg. Adding to his force were two newly arrived Corps from the Western Front, the Guards Reserve Corps and the XI Corps. For the first time since the opening of the war, the Germans now had numerical superiority. Then, like Rennenkampf, Hindenburg fed his newest troops into the northern end of the line and planned an offensive against the south. But unlike Rennenkampf, Hindenburg had enough forces not only to cover the entire front in the Insterburg Gap, but had additional forces "left over". He sent his most capable units, the I Corps and XVII Corps, far to the south of the lines near the middle of the Lakes, and sent the 3rd Reserve Division even further south to Lyck, about 30 miles from the southern end of Rennenkampf's line.

Hindenburg's southern divisions began their attack on the 7th of September, with the battle proper opening the next day. Throughout the 8th of September the German forces in the north hammered at the Russian forces facing them, forcing an orderly retreat eastward. In the south, however, things were going much worse. The German XVII Corps had met their counterpart, the Russian II, but were at this point outnumbered. The II maneuvered well, and by the end of the day had managed to get their left flank into position for a flanking attack on the Germans, potentially encircling them.

However, all hope of a victory vanished the following day when then the German I Corps arrived in support of the XVII; now the Russians were outflanked. Meanwhile the 3rd Reserve Divisions had engaged the Russians' XXII Corps even further south, and after a fierce battle forced them to fall back southeastward; its commander wired Rennenkampf he had been attacked and defeated near Lych, and could do nothing but withdraw. Rennenkampf ordered a counteroffensive in the north to buy time to reform his lines, managing to push the German XX Corps back a number of miles. However the Germans did not stop to reform their lines but instead continued their advances in the south and north. This left the victorious Russian troops isolated, but they were able to retreat to new lines being set up in the east.

Now the battle turned decisively in the Germans' favor. By 11 September the Russians had been pushed back to a line running from Insterburg to Angerburg in the north, with a huge flanking maneuver developing to the south. It was at this point that the threat of encirclement appeared possible. Rennenkampf ordered a general retreat toward the Russian border, which happened rapidly under the protection of a strong rear guard. It was this speed that enabled the retreating Russian troops to escape the trap Hindenburg had planned for them. The German commander had ordered his wings to quicken their march as much as possible, but a trivial accident — a rumor of a Russian counterattack — cost the Germans half a day's march, allowing the Russians to escape to the east. These reached Gumbinnen the next day, and Stallupönen on the 13th. The remains of the First Army retreated to the safety of their own border forts. Likewise, the Tenth Army was forced back into Russia.