R. F. Delderfield 
To Serve Them All My Days 

Miner’s son David Powlett-Jones returns from the carnage of the Western Front in 1918, shell-shocked and bitterly hardened by the violence of war. He begins life again as a master at a remote Devon school, controlling the destiny of boys barely his junior.As the years pass David becomes a teacher of rare talent, begins to find peace, and is able to adjust to the changes which are overwhelming society. But soon he will have to face up to the prospect of another terrible war…