Which battle was the most important one in World War One? The theme of the war was a huge military effort that involved many battles and about 70 million soldiers, 9 million of which were killed. It is extremely difficult to decide which battle is the most important due to these factors. Of the many important battles, I have chosen to summarize a few and to choose one as the most important. The first really important battle was the first battle of the Marne. In this battle the heavily outnumbered French forces held off the first German invasion at the Marne River. This battle forced the Germans to regroup North of the Marne and destroyed the Schlieffen Plan.
The Schlieffen Plan was the German plan of attack. Its objective was to knock the French out of the war before Russia would conquer eastern Germany. It unleashed three quarters of the German army in a giant westward sweep across Belgium and Luxembourg, and then into a giant wheel South into France.
This plan accepted the risks of an early Russian attack on the eastern front, so when the French destroyed it the German objective wasn't attained and it left the Russians with an open window for an attack. The Russians took this opportunity and attacked, which brings us to our second most important battle.
The Russians sent two armies into Germany that met in Tannenberg. Due to an error one army arrived before the other, but still had superior numbers. The battle of Tannenberg was a lot like the First battle of the Marne. In it and overwhelmed and outnumbered defensive force destroyed an offensive force that had superior numbers. The Germans completely destroyed the first army that arrived then launched a counterattack...