Basically, leaving aside the emotional dramas of my own pretend people, if something happened in the book, it happened to the Smith Unit. The Unit was founded in April of 1917 by Harriet Boyd Hawes, a highly eccentric and volatile pioneering archaeologist and humanitarian who delivered a stirring speech at the Smith College Club in April, pulled together volunteers, backers, and supplies with record speed, and embarked on the Rochambeau with a brand-new Smith College Relief Unit in uniforms of gray （with touches of French blue） in late July.
Wherever I could, I stuck with their own experiences and timeline. There wasn’t enough room in the inn when they arrived at Paris; they did wrangle an attic to sleep in. The chauffeurs did have to go to Saint-Nazaire to put their trucks together. Their agriculturalist, Frances Valentine, was delayed in DC, leaving another member to fill in—and that other member did accidentally buy roosters instead of chickens. The Unit did visit the American Ambulance Hospital in Neuilly, where a member fainted, and later dropped out entirely. The incident with a small child, who was hit by a ball and began screaming, thinking it was a bomb, was taken from a letter by a distraught Unit member. Kate and Emmie’s terrifying experience with the poilus at a deserted inn, including rescue by Canadian Foresters, came directly from the letters of Marjorie “Pidge” Carr and Catherine Hooper. Two Unit members were indeed sent to ask a very important official about acquiring poultry and wound up being lectured about pigeons.
Most dramatically, I discovered that, yes, there was a coup within the Unit and the sudden disappearance of the director, Harriet Boyd Hawes, was not, as it was put out in the public materials, for health reasons, but because of a deliberate campaign to remove her, a coup driven partly by personality, and partly by a disagreement about the nature of the Unit. As in the book, the faction succeeded in removing Hawes, who was replaced as director first by the Unit’s doctor, Alice Weld Tallant, and then by Hannah Andrews （the Mrs. Barrett of the book）， but not in altering her vision for the Unit. And, yes, the Smith College Relief Unit did ignore British orders to evacuate during a German onslaught and, instead, drove right into the fray and evacuated their villages. Everything you read about the March 1918 invasion in the book, the Smithies did, including directing traffic for the Great Retreat. Even more remarkable, they all came through unscathed in real life as well as in my fiction.
I did bend the truth in places. You may have noticed that although there are references throughout the book to there being eighteen original Unit members, if you count the named characters, there are actually only fifteen. That was because I found it impossible to keep eighteen personalities straight—and if I couldn’t keep track of them, how would my readers? It also replicated my experience reading the letters, where some members certainly stood out more strongly than others, with a core of perhaps ten who seemed to play the largest role in the Unit’s dramas and made for the best copy. My apologies to anyone who actually did the math and realized I was three characters short.
If there’s an incident in the book, it almost certainly happened, but I may have moved it or conflated events for simplicity’s sake. In the book, all of the women drive down to Grécourt together. In real life, one chunk of the group went to Grécourt on September 11, as described （issues with a pass, breakdown, loaned poilus, and all）， while another chunk stayed in Paris and came down a few days later. In the book, Emmie is delighted at having wrangled benches for their schoolhouses （keeping a French bureaucrat from his lunch!） in October. In real life, that exact incident happened in January. In the book, Margaret has a breakdown after seeing a boy who had been deliberately maimed by the German occupiers. In real life, that didn’t happen to the girl who dropped out. It did happen, but to a different Unit member, and later in the year （that Unit member wrote home that she’d seen something so shocking it had changed her whole life and made her decide to stop shilly-shallying and accept the proposal of the man she loved）。 And so on.
I also used real events as inspiration for fictional twists. Kate going missing at the end of the book was my own invention, but it was inspired by two Unit members being left at the crossroads in Roye and other Unit members defying Dr. Baldwin’s instructions and going back for them. There was, in fact, an English major （not a captain!） who gifted the Unit with duckwalk, but Captain DeWitt was entirely my own invention, even if Unit romances were not—there was at least one marriage that came out of the Unit’s adventures. As one member reported in her letters home, there were a number of “affairs” in progress between Unit members and their various admirers but very little privacy in which to conduct them.