This paper examines the historic but tragic first human vertical rocket flight which took place in south-western Germany on 1 March 1945. The primary lesson learned from the flight was that, as a result of the combination of psychological and physiological stresses, a human pilot could not be expected to fly a vertically launched rocket manually. An autopilot would be essential for the guidance of the Natter rocket interceptor up to its operational altitude. No further human vertical rocket flights took place until 1961 when Major Yuri Gagarin was launched into orbit. In early April 1945 a fully operational Natter flew successfully into the lower stratosphere under the control of a three-axis autopilot and crewed with a dummy pilot. Both dummy pilot and rear fuselage were recovered successfully under separate parachutes. In less than a year the engineers and scientists in collaboration with aviation physicians and physiologists at research institutions across Germany had laid down the basic principles which still apply to human rocket flight today.