The first permanent international organization built to keep world peace, founded in 1920 after the First World War on the principle of collective security. Headquartered in Geneva and eventually some sixty members strong, it pioneered cooperation on health, labor, and refugees while proving too weak to stop the aggressors of the 1930s. The United States never joined, the League had no army, and it collapsed into a second world war — yet it became the blueprint for the United Nations.
After a war that killed millions, the victors tried something no one had ever managed before: a standing parliament of the whole world, meeting in Geneva, with the job of stopping the next war before it started. The League of Nations was a magnificent idea. It also failed. The country whose president dreamed it up never joined, because its own Senate said no. The League had no army, so it could scold an invader but never stop one. When Japan, Italy, and then Germany took what they wanted by force, the League protested, and the aggressors simply walked out the door. Within two decades it stood by as the world fell into a far worse war. And yet, when that war ended, the survivors did not abandon the idea. They built it again, stronger, and called it the United Nations.