sentences:  He was an officer in the 1st Canadian Field Ambulance during World War I, reaching the rank of Lieutenant-Colonel, and later served as Director of Medical Services for the Canadian Expeditionary Force, serving as a Brigadier-General.Ross was credited with being the first to find measures to combat "trench foot" and the effects of mustard gas, as well as being the first to use light relays to evacuate the wounded.He stated that, regarding the Battle of Vimy Ridge, "...in those few minutes I witnessed the birth of a nation."