Friedrich August von Hayek was an influential economist and philosopher known for his defense of classical liberalism and free-market capitalism against socialist and collectivist thought. He is widely regarded as one of the most important economic thinkers of the 20th century. Hayek served in World War I and later moved to Britain in the 1930s, where he became a British citizen. His work was influential in the revival of laissez-faire economics in the late 20th century, and he was awarded the Nobel Memorial Prize in Economic Sciences in 1974.