In this episode our story focuses on the railways on the frontline - moving troops to the front, rescuing them when they retreated, evacuating civilians, suffering nightly bombardment during the Blitz and playing a vital role in the build up to D-Day. Dan explores the work and heroism of the railway men and women as well as exploring the vital technology and engineering that kept the railways running during this turbulent historical period. Dan's journey starts on the line to Dover. In both the First and Second World War, thousands of troops left from here for France. Although this period saw train disasters, the worst maritime disaster in history, the sinking of the Lancastria, it had at least as tragic an outcome for the many railway engineers travelling aboard. On the 17th of June, 1940 the Lancastria came under attack, she received three direct hits; the former ocean liner sank, taking with her an estimated 4,000 victims, many of them railwaymen.