Complex sentence: The period of the American Civil War and the immediate aftermath of Reconstruction saw another shakeup in the Supreme Court and legislation about same, which culminated in the Judiciary Act of 1869, the last piece of legislation which altered the size of the Supreme Court.
Split into simpler sentences: The period of the American Civil War and the immediate aftermath of Reconstruction saw another shakeup in the Court and in legislation concerning its size. This culminated in the Judiciary Act of 1869, the last piece of legislation which altered the size of the Supreme Court.