Known best for his Wolfson History Prize-winning work Iron Kingdom: The Rise and Downfall of Prussia, 1600-1947, Clark also published a biography of Kaiser Wilhelm II and a Los Angeles Times Book Prize-winning work titled The Sleepwalkers: How Europe Went To War In 1914.
After completing his undergraduate education at the University of Sydney and the Freie Universitat Berlin, he earned his doctorate in history from the University of Cambridge.
In the early 1990s, he began teaching in Cambridge's Modern European History department.
His marriage to art historian Nina Lubbren resulted in sons named Alexander and Josef.
He and early 20th-century writer G.M. Trevelyan were both Cambridge-educated historians.