The pacifists failed in their near-term goal, certainly, but that isn’t the whole story. Kazin reminds us that the meaning of the pacifist movement in World War I is still manifesting and evolving. “A grand cause that fails may, sometimes, matter as much as one that succeeds,” Kazin writes. “That failure can mark, with a bright line, a moment when a people and their government might have avoided making a decision that fundamentally changed their society.”

The eventual failure of the pacifist movement to keep the nation out of war obscures the fact that it did succeed, from 1914 to early 1917, in delaying U.S. involvement by building a broad coalition that was firmly rooted both in electoral politics and in social movements for equality, especially the suffragist movement.

One of the most notable politicians in the fight, Robert La Follette, a Republican senator from Wisconsin, failed to persuade his colleagues but used his platform to boldly critique the buildup to the war, and then war itself, as a profiteering mission in which the only parties sure to benefit were industrialists.

The tension between that critique of war and Wilson’s high-minded rationale for entering it imbues the story of American involvement in World War I with a tragic hue and an enduring fascination. As escalating nationalism made the declaration of war all but inevitable, Wilson positioned himself—and the nation—as the redemptive forces that would bring about a just peace and prepare the soil in which democracy could take root across Europe.

That was a deeply appealing message for progressives. War Against War’s great strength is in laying out the pitfalls and fractures the pacifist movement confronted—seduction by Wilson’s idealism, along with the pull to take part in other, equally urgent causes—while showing how it created a strong enough base, and a powerful enough critique, to push back against U.S. entry for three years.