ONE HUNDRED AND fifty years ago this July, Union and Confederate armies clashed close to the Pennsylvania town of Gettysburg. Although few realised it at the time, this three-day battle – a Union victory – was to become a defining moment of the American Civil War.“The world will little note, nor long remember what we say here,” declared Abraham Lincoln in his Gettysburg address, “but it can never forget what they did here”. He may have been wrong on the first count but he was indisputably correct on the second. Gettysburg, and the American Civil War as a whole, continue to loom large in history, not only in the United States, but in the world at large. For, as James M McPherson writes on page 98, “the international consequences of a divided America in two world wars and the Cold War are incalculable”.On the 150th anniversary of Gettysburg, we atBBC History Magazinehave created this American Civil War special edition, bringing together a group of leading American and British historians to tell the story of the conflict in a fresh, compelling manner. Over the pages that follow you will discover the key events and personalities that shaped the course of the war and also get a feel for what it was like to be a foreign mercenary, a southern widow or a wounded veteran during these turbulent years. I hope you find it a stimulating read.