Germany thought that it would take Russia approximately 6-8 weeks to get ready for war, no earlier.
France, on the other hand, was putting pressure on Germany to get their army ready faster. France even attacked East Prussia (in Germany) to scare them, and make their armies get ready faster. .
Russia didn't have enough weapons to supply their army of about 2.5 million men, so every other man had a gun, and on top of that, they had very bad training. .
The General of the 8th German Army (500 000 men who stayed back to protect Germany from Russia) was Max Vonprattwitz. Max Vonprattwitz saw the Russians coming to attack East Prussia (the spiritual capital of Germany), so Max Vonprattwitz retreated. Most of the men in his army were from Prussia and they got very angry at the fact that Max Vonprattwitz let Prussia get attacked. Herman Von Francois (Core Commander- like second in command) liked to fight, and hated Russia a lot. Herman Von Francois disobeyed Max Vonprattwitz and attacked Russia's 1st and 2nd army separately; he didn't even have 100 000 men. .
Russia's 1st and 2nd army got separated when the 1st army got stuck in a swamp. Once they were separated, Herman Von Francois took advantage of this, and attacked. All of Herman Von Francois's men were from East-Prussia, so they knew their way very well. They were able to place traps and kill people easily. One day Herman Von Francois and his army found Russian people lost in the woods. Herman Von Francois shone car headlights on the camp so the Russian's couldn't see where they were going and Herman Von Francois's army killed all the Russians. .
Paul Ludendorff replaced Max Vonprattwitz because they thought he made a bad decision by not siding with Herman Von Francois about attacking the Russians.
In 1917 Russia got knocked out of war along with Germany. Once Germany was out of they war, they sent help to France.
On the other side of Europe, France and Britain were in stalemate.