After President Trump bombed Iran, Democrats in Congress declared the action illegal. But it follows a long history of increased presidential control of military operations along with congressional deference and abrogation of war powers. How did we get here? Casey Dominguez finds that although the founders bestowed war powers with Congress, by the Spanish-American war legislators had expanded their view of the president’s powers and begun applying a more expansive view to their own party’s presidents. The role of nationalism, the rise of American power, and polarization all have echoes today.