John was born in January 1893 in Holyhead, Anglesey, Wales. He attended Oxford and was a member of the Officer Training Corps. He joined the Middlesex Hospital when only 16-years-old, and it was while he was in London that he joined the University of London Officers Training Corps, obtaining a commission in the Royal Welch Fusiliers in 1914. He was with them in camp when war was declared. Being anxious to qualify, he was seconded to complete his medical studies. After obtaining his degrees, he joined the Royal Army Medical Corps. He was stationed in Egypt and in March 1917 during the First Battle of Gaza won the Military Cross for bravery attending to the wounded. On 6 November 1917, during the Battle of Hareira and Sheria, he performed the deeds for which he would be awarded the Victoria Cross. The London Gazette reported:

"For most conspicuous bravery displayed in action until he was killed. Capt. Russell repeatedly went out to attend the wounded under murderous fire from snipers and machine guns, and, in many cases where no other means were at hand, carried them in himself although almost exhausted. He showed the highest possible degree of valour."

He is buried in CWGC Beersheba War Cemetery, F. 31.