Winthrop Bell was in the midst of completing the requirements for his doctorate in 1914 when Britain declared war with Germany on August 4. He was awakened that night and taken into protective custody.
"After two or three days I was allowed to return to my own rooms, reporting twice a day to the Police and keeping within the "Weichbild" [confines] of the town. A couple of weeks later I was arrested on a charge against me by a woman living near my dwelling (the charge amounted to incitement to disaffection on [a] public street, and the whole affair was silly in the extreme). At any rate, from then on I was in and out of prisons." 
On January 11, 1915, Bell was told that he would be transferred from Göttingen to the Ruhleben ["peaceful life"] Prison Camp on the site of a racetrack in the Spandau section of Berlin. He arrived on January 12 and moved through a few of the barracks including: Barrack 11, Box 27 (April 1916), Barrack 6, Box 18, (August 1916), and Barrack 3, Box 10 during the summer and fall of 1918 .
Ruhleben began receiving prisoners in September of 1914 but it was not until November 6, 1914, that the bulk of the population began to arrive. The men lived in stables that had been used for horses and six men were required to share one horse box that was ten feet square. Those not fortunate enough to receive a box were forced to sleep in the open hay lofts or in one of the other rudimentary buildings on the site. By March of 1915 there were approximately 4,400 men and boys interned at the Ruhleben Camp. 
Living conditions were poor. Few of the stables had lights or electricity, initially there were no provisions made for additional clothes with which to face the cold winter weather, and the meals were meager at best. The men rapidly began to work together to demand improvements and also organized many societies to boost morale and to order their own community.
While interned Dr. Bell regularly attended lectures in architecture, history, French, and philosophy. He was also called upon to teach and there is evidence in his papers of a lecture he prepared on the subject of Canada. While he was interned at Ruhleben he naturally gravitated towards other intellectuals and established lasting friendships with Sir Ernest MacMillan, Dr. A. Grant Lochhead, Michael Pease, and Hans Jannasch (son of a Moravian missionary born in Labrador).
Winthrop Bell spent the balance of the war at the camp and was hit hard when he received the news of his father's death on October 8, 1918.
After the war concluded he stayed for some time in Berlin trying to make arrangements to get out of the country. He ultimately made it to England on November 27, 1918. The long war years were finally over.