The documentary concludes with the story of the raid on Germany's dams, which got off to a rocky start as two of the Lancaster bombers were forced to return home damaged, while a third was destroyed by enemy fire. As the crews made their way across Europe, more planes were lost and the first attempts to destroy the dams failed. But then 21-year-old pilot David Maltby and his crew released their bomb and breached the dam with devastating effect. After this point, the targets were destroyed - but at a shocking cost. Presented by Dan Snow.