He worked as a reporter before enlisting in the Royal Army Medical Corps in the ranks when World War I broke out.

When fighting with his platoon in the forward position of the battle zone, 2nd Lt. Buchan, although wounded early in the day, insisted on remaining with his men, and continually visited all his posts, encouraging and cheering his men in spite of most severe shell fire, from which his platoon was suffering heavy casualties.

Eventually, when he saw the enemy had practically surrounded his command, he collected his platoon and prepared to fight his way back to the supporting line.

At dusk he fell back as ordered, but in spite of his injuries again refused to go to the aid post, saying his place was beside his men.

The gallantry, self-sacrifice, and utter disregard of personal safety displayed by this officer during these two days of most severe fighting is in keeping with the highest traditions of the British Army.He was buried at Roisel Communal Cemetery Extension, Roisel, Somme, France (Plot: II.