Columbia subject headings:
Harvard subject headings:
Social history--19th century--Congresses.
Social history--20th century--Congresses.
War and society--Europe--Congresses.
War--Congresses
Princeton subject headings:
Europe--History, Military--18th century.
Europe--History, Military--19th century.
Europe--History, Military--20th century.
Nationalism--Europe--History.
War and civilization.
War--Psychological aspects.