You will be given a definition of a task first, then some input of the task.
Generate a correct and concise answer for the question based on the words in the context.

Context : Captain William Victor Trevor Rooper (10 May 1897 -- 9 October 1917) was a British World War I flying ace credited with eight aerial victories, before becoming Xavier Dannhuber's seventh victim.
Question : In what war was William Victor Trevor Rooper a combatant?
Output:
World War I