Chadwick and Ellis at Ruhleben

Earlier this week I took a book, "Biography of Physics" by George Gamow out of the University Library.  It was published in 1962, costing one guinea.  As far as I can find out, it seems to contain the oldest reference to the work of J A Wheeler on toroidal nuclei, in a passing comment.  This is the reason I wanted to refer to the book.  In reading the section on nuclear physics, though, I learnt something that is presumably fairly well-known, but that I didn't know.

At the start of the First World War in 1914, James Chadwick was working at the University of Berlin, and was interned as an enemy alien for the duration of the war, in the Ruhleben camp on the outskirts of Berlin.  Gamow writes "The first year in the camp was dull, since the young and talented physicist could not make any friends among his fellow prisoners, consisting mostly of businessmen, travelling salesman, etc.  Then after a big battle somewhere in France, a new prisoner appeared in the camp.  He was C. D. Ellis, a brilliant officer of His Majesty's Highland Regiment, who had been captured on the field of battle.  The two Britishers became friends and, to kill time, Chadwick started teaching Ellis the facts of nuclear physics.  When the war ended, both returned to England and Ellis enrolled as a graduate student of Cambridge University where Chadwick was a lecturer.  A few years later, Ellis published a paper which represented an important extension of Chadwick's work."

I did not even know that Chadwick had spent the war years interred in Germany, and certainly not that a soldier was converted into a physicist by Chadwick.  Looking up Ellis online, the story told is slightly different, in that Ellis is said to have been holidaying in Germany in the summer of 1914 just after passing out first of his class from the Royal Military Academy.  He was therefore also interned at the beginning of the war.  This information seems to stem from Ellis's entry in the Biographical Memoirs of the Royal Society (Sir Kenneth Hutchison, F. R. S., J. A. Gray and Sir Harrie Massey, F. R. S., Biogr. Mems Fell. R. Soc. 1981 27, 199-233 doi:10.1098/rsbm.1981.0009), though in that source they say that in later life he destroyed all his personal records, papers and letters, and hence there was some difficulty in reconstructing his biography.  They seem, though, to have only given information that they are pretty sure of, so I suspect Gamow's account is not right.  Anyone reading know more to the story?