Swashbuckling stories of the Union naval blockade of the Southern states and the blockade runners who smuggled goods to the Confederacy have long been a part of the romanticized image of the Civil War. Throughout the war, Lincoln’s blockade and attempts to breach it touched nearly every aspect of the war effort. The Union prevented crucial material from reaching Confederate forces, while blockade runners smuggled hundreds of thousands of guns to rebel armies. No other military campaign lasted as long or had as many long-term consequences on the outcome of the Civil War. Covering more than three thousand miles of Southern coastline and employing the services of 100,000 sailors, the blockade was a massive undertaking largely dictated by two Atlantic powers: Great Britain and the United States. Michael Bonner and Peter McCord build on the extensive scholarship of the blockade and incorporate previously unexamined British primary sources to deliver a fresh analysis of the Union blockade, blockade-running, and a reassessment of the blockade’s effectiveness. Their multifaceted study reassesses several key aspects of a “critical component of Union strategy,� including diplomatic and legal issues and the significance of the Confederacy’s reliance on European supplies to sustain the war effort. The authors present statistics showing that the blockade was not nearly as effective as is commonly believed; moreover, its successes against steam-powered blockade runners actually decreased as the war went on. The diversity and comprehensiveness of coverage makes The Union Blockade in the American Civil War an essential work for Civil War historians and students.