James Churchill Dunn (1871–1955) was a British medical officer during World War I, and author. He is known for his memoir The War the Infantry Knew, first published in 1938.
Dunn, who had previously served in South Africa, was Regimental Medical Officer for the Royal Welch Fusiliers during World War I, and is mentioned in the memoirs of both Robert Graves and Siegfried Sassoon. Dunn wrote of his official role that: "The first duty of a battalion medical officer in War is to discourage the evasion of duty ... not seldom against one's better feelings, sometimes to the temporary hurt of the individual, but justice to all other men as well as discipline demands it."
Dunn's memoir was originally published anonymously, in a private limited edition, and has been described as "a magnificent tour de force, the length of three ordinary books"
The work includes an account of the Christmas truce of 1914. Dunn describes the resumption of hostilities as follows: "At 8.30 I fired three shots in the air and put up a flag with "Merry Christmas" on it, and I climbed on the parapet. He [the Germans] put up a sheet with "Thank you" on it, and the German Captain appeared on the parapet. We both bowed and saluted and got down into our respective trenches, and he fired two shots in the air, and the War was on again."