Book excerpt: The joint British and US campaigns in the European theater of operations during World War II rank among the most impressive examples of coalition warfare in history. In just eighteen months, the US and British armies integrated their planning, intelligence, and command structures more thoroughly than any previous alliance. Millions of British and American soldiers fighting alongside one another liberated North Africa, France, Italy, and western Germany. How did these two armies come together so quickly? How did they combine their forces to a degree never before seen among the services of sovereign nations? And how did they sustain their alliance in the face of severe disagreements and battlefield setbacks? In Forging the Anglo-American Alliance, Tyler Bamford answers these questions by presenting the first history of the two armies’ relations from 1917 to 1941. Great Britain and the United States emerged from World War I as the strongest military powers in the world. Forging the Anglo-American Alliance examines why the armies of these two nations chose to view each other as their closest strategic partner instead of their greatest potential threat and illustrates the legacy that World War I had on the attitudes of the US and British armies toward one another and alliance warfare. Through personal interactions and military education in the years leading up to World War II, army officers shared large amounts of military intelligence and formed positive opinions of one another. As the threat of Germany and Japan grew, army officers were the first to anticipate the need for an alliance between their nations and to begin thinking about ways to structure their combined forces. Using untapped archival sources, official reports, and officers’ personal papers, Bamford presents an important and engaging new analysis of how this partnership grew out of the experiences and initiative of British and US Army officers and attachés during World War I and the two decades that followed.