ABSTRACT. In The Shaping of America Donald Meinig describes a United States averse to challenging Britain geostrategically but emerging as a powerhouse economy by the late 1890s. But America embarked on a sustained economic struggle with Britain in 1861 by embracing protectionism; America's Civil War ironclads were as much to resist Britain as fight the Confederacy; and in 1866 ussMiantonomoh helped persuade Britain to reconsider, then pay, the Alabama Claims. Britain never retaliated in the economic struggle by moving to protectionism and in the late 1800s began to appease America in geostrategic terms. This struggle intensified in the 1920s and 1930s as America and Britain competed for control of international transportation, international communication, and the global oil supply, but by the mid-1940s American hegemony was clear. This article traces the course of the complex economic and political struggle for hegemony in the light of recent models of transitions in the world economy.