The 12th Light Dragoons served throughout Wellington's campaigns in the Peninsula, most notably at the Battle of Salamanca in 1812, and later at Waterloo where they suffered heavy casualties supporting the Union Brigade's famous charge. The principal source for this book are the papers of Sir James Steaurt - Colonel of the regiment for almost all of the period in question - supplemented by other regimental records, Horse Guards paperwork, and letters and memoirs, allowing both an official understanding of events, and several threads of human interest which develop through the narrative. The book is divided into two halves, first providing an overview of the regiment and the role of Steuart as Colonel, before moving onto an account of the regiment on home service during the early years of the Napoleonic Wars and then on active service in the Peninsular War and at Waterloo. This concludes with a discussion of the lessons learnt during the war, as particularly exemplified by the 12th being one of the regiments selected for conversion to lancers in the aftermath of Waterloo.