The S class (initially known as the Modified "Trenchant" class) was a class of 67 destroyers ordered for the Royal Navy in 1917. They saw active service in the last months of the First World War and in the Russian and Irish Civil Wars during the early 1920s. Most were relegated to the reserve by the mid-1920s and subsequently scrapped under the terms of the London Naval Treaty. Eleven survivors saw much action during the Second World War.