This work investigates the historical tension between liberal political ideology and the necessity or morality of engaging in warfare. Michael Howard, a distinguished military historian, examines how liberal thinkers have historically grappled with the paradox of promoting peace while simultaneously justifying military intervention. He analyzes the evolution of liberal thought from the Enlightenment through the twentieth century, arguing that the liberal conscience is perpetually caught between universalist ideals and the realities of power politics.

Historians and political scientists frequently cite this text as a foundational analysis of the intellectual history of modern warfare. Readers often note the clarity of Howard's prose, which makes complex ideological shifts accessible to both academic and general audiences.