During the 20th century, historians John Gallagher (1919–1980) and Ronald Robinson (1920–1999) constructed a framework for understanding European imperialism. They claim that European imperialism was influential, and Europeans rejected the notion that "imperialism" required formal, legal control by one government over another country. "In their view, historians have been mesmerized by formal empire and maps of the world with regions colored red. The bulk of British emigration, trade, and capital went to areas outside the formal British Empire. Key to their thinking is the idea of empire 'informally if possible and formally if necessary.'"[attribution needed] Because of the resources made available by imperialism, the world's economy grew significantly and became much more interconnected in the decades before World War I, making the many imperial powers rich and prosperous.