Anti-Catholicism has had a long presence in American history. The Civil War in 1861 gave Catholic Americans a chance to prove their patriotism once and for all. Exploring how Catholics sought to use their participation in the war to counteract religious and political nativism in the United States, Excommunicated from the Union reveals that while the war was an alienating experience for many of 200,000 Catholics who served, they still strove to construct a positive memory of their experiences in order to show that their religion was no barrier to their being loyal American citizens.