The American Civil War lives in our national memory as a great inflection point that reshaped the country. Indeed, the sense that the Civil War created “another world” has dominated much of the writing on its history ever since William Dean Howell published The Rise of Silas Lapham in 1884.

At the turn of the century, progressive historians like Charles and Mary Beard described the Civil War as a “second American Revolution.” More recent progressives, like Eric Foner and David Blight, have emphasized a new legal world—a “second founding,” as they say—in which the Thirteenth, Fourteenth, and Fifteenth Amendments transformed the old Constitution’s passive restraints on the federal government into activist powers that could advance the cause of equality.

Fergus Bordewich’s newly released book, Congress at War: How Republican Reformers Fought the Civil War, Defied Lincoln, Ended Slavery, and Remade America, joins this chorus of assent. It argues that the Civil War “laid the foundation for the strong activist central government that came fully into being in the twentieth century, permanently altered the relationship between the states and the federal government, and enshrined protection of civil rights as the responsibility of the federal government.”

That’s not necessarily a novel observation, but Bordewich differs from previous historians through his depiction of Congress’s role in that transformation. Past accounts have relegated the 37th and 38th Congresses in creating an “activist central government” to little more than the role of a bystander. America’s 16th president, in their view, is essentially the lone hero. But it was the Republican-dominated Congresses that made the “steady march toward more effective and centralized government,” while the Great Emancipator struggled to play catch-up, Bordewich insists.

Even Abraham Lincoln’s Emancipation Proclamation is really “a result of the many months of debate in the House and Senate, and the ceaseless personal prodding of the Radicals in Congress.” The Great Emancipator thus becomes almost the Great Fifth Wheel.