Alexander Wishart enlisted with the 7th (Fife) Black Watch, probably in Fife during April 1916, and eventually gained the rank of acting corporal. Unfortunately his service papers have not survived; however, it is known that at some point he was transferred into the 2nd Gordon Highlanders and saw active service in Italy during 1918. On 20 May, he fell ill with suspected trench fever and sent onwards from the 21st Field Ambulance to the 31st Ambulance Train, where he transferred to the stationary hospital in Genoa. Six days later Alexander was discharged back to duty having recovered from a fever of an unknown origin. A regimental history of the Gordon Highlanders notes that around this time about 200 men from the battalion were stricken with similar symptoms to the extent that a toxicologist came from France to investigate.
Alexander ended his war in Italy, with another trip to the field ambulance being necessary several days before the Armistice due to a bout of influenza. It seems likely he left for home towards the end of December.