Katharine took a break in the spring and early summer of 1918, but returned to France to Pontoise and the Hospital Militaire, Caserne de Cavaliere from July 16 to November 11, 1918. She also spent time in a German hospital in Langenschwalbach from January to May 1919. Her friends, Edith Parkman and Helen Homans, were her constant companions at work and her sightseeing partners on breaks. Her letters home are filled with descriptions of her daily activities, amusing stories, touching reminiscences of the wounded soldiers, and questions and comments about people back home. Katharine had developed an interest in photography and she kept scrapbooks of the haunting images she took of her experiences in France. The brutality and cruelty of the war was disturbing to her however, and this comes through in the sketches she made of the soldiers in the hospitals. As the war dragged on, Katharine's correspondence expressed a tiredness with the situation and more specifically, with the lack of trained nurses. Katharine returned from war wiser and more self-assured. Her nursing experience had transformed the shy, sheltered girl into a more confident and independent woman, who would continue to serve local Red Cross and Victorian Order of Nurses chapters in Cape Breton. Service at the Fortress of Louisbourg One of Katharine McLennan's greatest interests was history, specifically the history of the Fortress of Louisbourg in Cape Breton Island. For years she had traveled with her father to London, Paris, Boston, and Ottawa, to find information that could help to tell the story of Louisbourg, including the various sieges as well as the day-to-day life of the people who lived there during the 18th century. After World War I, Katharine, J.S. and other local supporters, like Archdeacon T.F. Draper from Louisbourg, lobbied to have the federal government preserve the Fortress of Louisbourg site. Their work led to the opening of the Louisbourg Museum in 1936 and the eventual partial reconstruction of the Fortress in the 1960s. Katharine was named "Honorary Curator" of the museum and served in this capacity for over twenty years. Katharine worked tirelessly to build the Louisbourg Museum. She used her contacts and financial resources to locate and retrieve artifacts from the time of French occupation, including a cannon at Halifax and the Louisbourg bells. As Curator, she was responsible for cataloguing artifacts, mounting displays, and coordinating special events. She wrote articles and gave talks