During World War II the United States abandoned its traditional fear of military alliances and joined one in order to defeat the mortal threat posed by Nazi Germany and its Axis partners. That alliance was highly successful and led not only to total victory, but also to the creation of an Anglo-American special relationship that has lasted for more than seven decades. Contrary to popular belief, however, the success of this alliance was not preordained. Indeed, it was marked by numerous and serious conflicts throughout the war that threatened on multiple occasions to destroy it. This lecture will analyze those conflicts and just how the Allies managed to overcome them.