The First Congress may have been the most important in American history, establishing how our new government would work based on principles that had been only broadly outlined in the Constitution. We asked the distinguished historian Fergus Bordewich to provide us with an overview of the first two years of the U.S. Congress and the challenges it faced. Portions of this essay appeared in Mr. Bordewich's recent book, The First Congress. His new book, Congress at War, due out in February 2020, will relate how Congress helped win the Civil War.