 A second difficulty in analyzing social entities is in distinguishing ontological from merely causal relations. In many cases, the distinction is straightforward. The Battle of the Somme, for instance, is part of World War I. That battle is not a cause of the war. It is a constituent of it: the Battle of the Somme is ontologically rather than causally related to World War I. The 1881 formation of the Triple Alliance, on the other hand, is causally related to the war, not ontologically.