It was thought that the ultimate antidote to war was universal democracy. It was not. Spencer defined liberal democracy as an individual free to control the product of his own efforts on the market. Welfare societies could not rationally be termed democracies.
Globalism perverts the Constitution. Meddling activism has unintended consequences like centralizing the power of the Presidency. Intervention creates blowback.
The effects of the Industrial Revolution are a major issue in Classical Liberalism. From 1750 to 1850 industrialization got slowly underway in Britain. Division of labor and urbanization were considered a catastrophe. It was thought that only labor unions could improve conditions of the working people. This myth created a standing presumption that laissez-faire ruins countries and requires state intervention to protect present victims of capitalism.
An optimist school made gradual headway against these pessimists. They gathered objective data and applied better economic theory. Wages, availability of foodstuffs, and length of life were finally considered in contrast to initial horror stories. In fact, the standard of living improved for most workers. Industrialization allowed tens of millions of people to survive as their populations exploded. The Industrial Revolution was not the problem; it was the solution.
Lecture 5 of 10 from Ralph Raico's History: The Struggle for Liberty.