He became a Sergeant Mechanic in March 1918 and was discharged in April 1920 .
In April 1915 , 9 months after the breakout of the First World War , Lappin enlisted as a sergeant in the Royal Flying Corps .
Lappin became a Sergeant Mechanic in March 1918 and was discharged in April 1920 .
In April 1915 , 9 months after the breakout of the First World War , Lappin enlisted as a sergeant in the Royal Flying Corps .