970
He returned to active service as a temporary reserve second lieutenant in 1915 , during World War I , and relinquished his commission in 1919 , still a second lieutenant .
 event: World War I
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 event: World War I