Moss was educated at Rugby and the Royal Military College, Sandhurst, and was commissioned into the Grenadier Guards in 1905. In the First World War he reached the rank of Major, before retiring in 1919 to devote himself to his writing. His first novel, Sweet Pepper (1923) – a romance novel set in the former Austro-Hungarian Empire in the aftermath of the First World War – was a bestseller and was followed a year later by the popular and influential short story collection, Defeat (1923). Thereafter Moss published roughly a book a year until the outbreak of the Second World War, his œuvre comprising novels, short story collections, verse, children's stories and works of non-fiction on European politics and military matters.
