James Stagg

Group Captain Sir James Martin Stagg, CB, OBE, FRSE (30 June 1900 – 23 June 1975) was a British Royal Air Force meteorologist who notably persuaded General Dwight D. Eisenhower to change the date of the Allied invasion of Europe in World War II, from the 5th of June to the 6th of June 1944.

Biography
Stagg was born in Dalkeith, Scotland. In 1924, he became an assistant in the British Meteorological Office and was superintendent of the Kew Gardens observatory in 1939. In 1943, he was commissioned a Group Captain in the Royal Air Force Volunteer Reserve and appointed the chief meteorological officer for Operation Overlord. Stagg was the senior staff meteorologist working with input from three separate forecasting teams from the Royal Navy, Met Office and USAAF. The detailed history of the forecasts is subject to disagreement in the accounts published by participants, including Stagg himself.

Stagg later worked as director of services at the Meteorological Office until 1960.

For his invaluable services during the planning of D-Day, Stagg was appointed an Officer of the US Legion of Merit in 1945 and was also appointed an OBE at the same time; he was knighted in 1954 and also appointed a CB that year. He was elected as a Fellow of the Royal Society of Edinburgh in 1951 and elected as president of the Royal Meteorological Society in 1959.

Stagg was portrayed by Patrick Barr in the 1962 film The Longest Day.