Harold Barclay (1872-1922) was born in New York City and grew up in his wealthy parents' country home by Lake Cazenovia, NY, resulting in his lifelong love of the country and dislike of cities. He entered Harvard but left after the first year to travel in Europe before studying music in Germany, and although tempted to make music his life's work, eventually decided upon a career in medicine. In 1899 he graduated from the College of Physicians and Surgeons, having acted as a medical assistant during the Spanish-American War. His love of travel and music remained throughout his life and he often took vacations in Europe and undertook scientific studies in France and Germany. In 1917 he received a commission as captain and went overseas in the Roosevelt Hospital Unit. Promoted to Major in February 1918, he was later transferred to the 42nd (Rainbow) Division in which he served during the heavy fighting at Ch?teau-Thierry and St.-Mihiel. In November 1918 he became a Lieutenant-Colonel and was ordered home on January 2, 1919. Dr. Barclay was traveling with his wife in France when his sudden death occurred at Biarritz in the summer of 1922. This wartime diary was privately printed in 1923 and includes a photographic portrait of the author.