In his return to civilian life after five years' Army service in the First World War, Vaughan Williams revised some pre-war works, such as The Lark Ascending and his opera Hugh the Drover, and embarked on new compositions - the Pastoral Symphony, the one-act Bunyan episode The Shepherds of the Delectable Mountains and the Mass in G minor - all of which have outwardly in common a serene tranquillity. But beneath the surface, especially of the symphony, is a requiem-like mood, a legacy of the war. This ambiguity can also be sensed in the three songs - or rondels - for voice and string trio which he called Merciless Beauty.