Battles of Stalluponen and Gumbinnen

Often, when people hear World War I, if they know anything about it, they probably will think of the trench warfare in France and Belgium. This Western Front's importance is obvious because of its proximity to Paris. Yet, many times people don't even think of the Eastern Front (between the Central Powers and Russia) , what I think was the 2nd largest front in terms of troops and size of battles. Many soldiers died there too, and while it was not critical, it is worth telling. This is about the first two major engagements in that region, the Battle of Stalluponen in present-day Lithuania, what was then German East-Prussia.

The Russian plan for attacking Germany involved sending their First and Second Armies into East Prussia in a two-pronged attack. Rennenkampf, the commander of the First Army, was advancing into Prussia. On August 17, 1914, the German I Corps, commanded by Francois, of it's Eight Army found them near Stalluponen. Francois, eager for some action, ordered an attack on the Russians. The latter were taken by surprise and subsequently were driven back to the border. The German commander of the Eight Army, von Prittwitz, was afraid the I Corps would be engulfed by the larger Russian force so he ordered the Germans to pull back to the town of Gumbinnen. Once again the Russians resumed their westward march.
Francois convinced Prittwitz to launch another attack against the Russians before it was too late. Prittwitz needed to defeat the Russian First Army before their Second Army got too close. The German Eight Army, about 150,000 men, advanced against the Russian First Army, 200,000 men. They met on August 20.

The first attack of the Germans was not quite perfect. While Francois' I Corps was fully ready and attacked when ordered, The XVII Corps under General Mackensen and the I Reserve Corps under von Below were several hours late.

At first Francois forced the unprepard Russians back some distance. Mackensen and Below were encouraged by this and tried to push the Russians back themselves. This time, though, the Russians bombarded these two with heavy artillery that allowed the Russians to make their own advances. With the German center and southern end in retreat, Francois had to pull back himself. General Prittwitz was disturbed by this large-scale retreat of his forces and ordered a complete general withdrawal, in case the Russian Second Army appeared.

Berlin was angry at the German failure and ordered Prittwitz back. They replaced him with General Paul von Hindenburg and his Chief of Staff Erich Ludendorff. These two managed to stop the German withdrawal. This time they turned around to attack the Russian Second Army at Tannenberg.

For a great site about World War I go here.