In the First World War, France fought on the side of the Allies. At the beginning of the First World War, Germany invaded through Northern France, attempting to capture Paris quickly. Meanwhile, France's plan for a war on Germany, Plan XVII, which involved an attack on Alsace-Lorraine, was quickly thwarted. Germany continued to advance into France but was halted north of Paris at the First Battle of the Marne. Both sides dug a long line of trenches, which resulted in a stalemate for four years until the Allies broke through in 1918. Following the First World War, France acquired Alsace-Lorraine, temporary economic control over the Saar Basin, and several other advantages.
