John Desmond Bernal (1901-1971) was an Irish-born scientist (from Nenagh, County Tipperary), known as a scientist who pioneered X-ray crystallography, and also as a communist activist. He was educated at Bedford School and Emmanuel College, Cambridge. After graduating he started research under Sir William Bragg at the Davy-Faraday Laboratory in London.

It was in his research group in Cambridge that Dorothy Hodgkin started her research. Other prominent scientists who studied with him include Rosalind Franklin, Aaron Klug and Max Perutz.

He was later Professor of Physics at Birkbeck College, University of London and a Fellow of the Royal Society. As well as practising science, he is famous as a populariser of science with works such as The Social Function of Science (1939) and Science in History (1954).

He was also prominent in political life, particularly in the 1930s after having left the Communist Party of Great Britain in 1933.

In 1939, he published "The Social Function of Science," probably the earliest text on the sociology of science.

He is known also as joint inventor of the Mulberry Harbour, and for proposing the Bernal sphere. A fictional portrait of him appears in the novel The Search, an early work of C. P. Snow.

After helping orchestrate D-Day, JD Bernal landed on Normandy on D-Day + 1. His extensive knowledge of the area stemmed from a combination of research in English libraries and personal experience having visited the area on previous holidays. The Navy had temporarily assigned him the rank of commander such that he wouldn't stand out as a civilian amongst the invasion forces. However, the members of his unit were less than convinced as he directed a vehicle using the terms "right" and "left" instead of "port" and "starboard."

Martin Bernal, author of Black Athena, is his son.

Reference

• Sage: A Life of JD Bernal (1980) Maurice Goldsmith