The Schlieffen Plan was Germany’s pre–World War I strategy for quickly defeating France in the west, then turning east to fight Russia, in order to avoid a long two‑front war.

Core idea in simple terms

  • Drawn up in 1905 by Count Alfred von Schlieffen, the German army’s chief of staff, it assumed that Russia would mobilize slowly while France could be knocked out fast.
  • The plan called for a huge German swing through neutral Belgium (and originally also the Netherlands) to encircle Paris from the north, crush the French armies, and force France to surrender within weeks.

How it was supposed to work

  • Most German troops would be placed on the right wing, sweeping through Belgium into northern France, while a much smaller force held the line against France in the east and watched Russia.
  • After defeating France, the bulk of the German army would be rushed by rail to the eastern front to face Russia, which planners believed would still be organizing its forces.

What happened in 1914

  • When war broke out in 1914, Schlieffen’s successor Helmuth von Moltke modified the plan, weakening the right wing and not invading the Netherlands, which reduced the speed and force of the offensive.
  • German forces advanced through Belgium but met stronger than expected resistance, supply problems, and rapid French and British responses; they were finally stopped at the First Battle of the Marne, leading to trench warfare instead of the quick victory the plan promised.

Why it matters today

  • Historians often use the Schlieffen Plan as a case study in how rigid, over‑optimistic war plans can fail once they meet real‑world complexity, terrain, logistics, and enemy decisions.
  • The violation of Belgian neutrality under the plan also helped turn international opinion against Germany and became a key symbol of German aggression in the story of World War I.

TL;DR: It was Germany’s gamble to win World War I quickly by smashing France first through a massive attack via Belgium, then turning on Russia—but in practice it stalled, helped trigger trench warfare, and ultimately failed.