Muck was arrested on March 25, 1918, just before midnight and therefore the BSO's performances of Bach's Saint Matthew Passion on March 26 and April 2, which Muck had been preparing for months, had to be conducted by Ernst Schmidt. Government officials were free to ignore the fact that he was a Swiss citizen and bearer of a Swiss passport, since the law sanctioned the arrest of those born anywhere in Germany before the founding of the German Empire without respect to citizenship. Boston police and federal agents also searched Muck's home at 50 Fenway and removed personal papers and scores. They suspected the conductor's markings in the score of the St. Matthew Passion were code indicative of pro-German activity. He was imprisoned at Fort Oglethorpe in Georgia until on August 21, 1919, an agent of the Department of Justice put him and his wife on a ship to Copenhagen. The Phi Mu Alpha Sinfonia music fraternity that had elected him to national honorary membership in 1916 expelled Muck in 1919 for sympathizing with the Central Powers. Fellow internees had heard that Muck had vowed in protest to never conduct in America again, but they persuaded him that the camp was more of a German village — some of them even called it "Orglesdorf." A memoir of the event written in 1940 recalled the mess hall packed with 2000 internees, with honored guests like their doctors and government censors on the front benches, facing 100 musicians. Under Muck's baton, he wrote, "the Eroica rushed at us and carried us far away and above war and worry and barbed wire." When sailing from New York harbor on August 21, 1919, Muck told reporters: "I am not a German, although they said I was. I considered myself an American." He admitted, however, to having "bitter feelings" toward the America news media over their biased and unfair treatment of him. He also expressed doubts that the BSO, which was in a sorry state of organization, would ever recover after the similar internment of 29 of its musicians. After his deportation, Muck declined all subsequent invitations to return to the United States. Later that year the Boston Post alleged that Muck had been having an extramarital affair with a 20-year-old in Boston's Back Bay and had written her a letter reading in part: "I am on my way to the concert hall to entertain