Death of younger son Bob at Gallipoli clouds William and Lawrence Braggs' Nobel Prize science honour in 1915

Lawrence Bragg's younger brother Bob died in a dugout on the Gallipoli battlefield.

At the outbreak of War World I, Lawrence Bragg and his brother Bob joined a territorial unit called King Edward’s Horse, a mounted infantry unit composed of men from British Dominions.

Lawrence applied for a commission and was assigned to the Leicestershire Royal Horse Artillery for year’s training in Norfolk. Bob also applied for a commission and joined the 58th Brigade of the Royal Field Artillery. In 1915, Bob sailed with his unit to Alexandria, where he found mixed bathing in the warm water was “just like out in Australia”.

In August, Lawrence was sent to France to superintend the developing of a French technique to determine the position of enemy guns by recording the time of arrival of their sound along the front. With other physicists, Lawrence developed sound ranging into a practical and accurate technique.

William Bragg was in Canada and America on a lecture tour, but he cut his visit and hurried back when his wife Gwendoline’s anxiously called him home.

In May 1915, the trustees of Columbia University awarded to William and and Lawrence the Barnard Gold Medal for their work on X-rays and crystals. In June, William accepted an invitation to go to University College, London, and resigned reluctantly from the University of Leeds.

In August, Harry Moseley, “the most promising of all the English physicists of his generation”, was killed at Gallipoli; and in September brought the news the Braggs feared most. Bob was sitting in a Gallipoli dugout when a shell came through the sand bags, severed his left leg and damaged the other beyond repair. He died hours later. Lawrence’s other great friend, Cecil Hopkinson, was also killed.

In November, William received a telegram from Sweden notifying him of the joint award with Lawrence of the 1915 Nobel Prize for physics.