When I began to write Somewhere in France, the character of Lilly came to me straight away, together with the notion that over the course of the novel she would break free of her conventional upbringing through the work she does during the Great War. What I wasn’t sure of, and in fact took months to decide upon, was the exact nature of that work.

At first I thought I would make Lilly a nurse, just like Vera Brittain, author of the classic memoir Testament of Youth. But since Lilly had no formal education, at least as I imagined her, and would have required several years of schooling in order to be considered for even the most junior of nursing positions, I knew I had to consider other possibilities.

There were many jobs she might have done as a volunteer or member of the women’s services, few of them requiring the sort of specialized training necessary for nursing. I could have made her a clerk, a laundress, a mechanic, a cook. But the work that intrigued me most was that of ambulance driver.

In the early years of the war, ambulance drivers (both of motor vehicles and horse-drawn wagons) were as likely to be volunteers as members of the military. The Army Service Corps (ASC) provided the lion’s share of drivers, all of them men. There were American volunteers, too, most notably the 2,500 members of the American Field Service, though this number decreased once the United States entered the war in 1917 and AFS members moved to join the U.S. military.

And there were many hundreds of woman drivers among the members of the First Aid Nursing Yeomanry (FANY), the Volunteer Aid Detachments (VAD) and the International Red Cross (IRC). Yet none of these fit my narrative, for I wanted a service that would accept Lilly even if she were estranged from her family and could provide little in the way of references. I wanted her to belong to a service that would have ordinary women as its members, with little of the veneer of exclusivity that characterized the FANY, for instance.

The one service that fit, the one I knew would make historical as well as narrative sense, was the Women’s Army Auxiliary Corps. Founded in 1917 with the intention of replacing men with women in non-combat roles, thus freeing up men for front-line duty, the WAAC had nearly 60,000 members by the end of the war. Although it was organized along lines that in retrospect appear elitist, with its senior positions filled almost entirely by upper-middle-class women, most of its members were women from decidedly modest backgrounds.

Unearthing detailed information about the WAAC proved to be unexpectedly difficult. Most of the official records relating to the WAAC were destroyed during the Blitz, and though the remaining information has been digitized and is accessible via the National Archives in the U.K., it still provides an incomplete picture of the corps and its members. Most of all, I needed to confirm the presence of WAACs at clearing hospitals closer to the Front, but reliable evidence was difficult to find.

One memoir often cited by historians is The Story of a WAAC, and it does place the narrator and a colleague firmly at a CCS, where they work not only as drivers but also as impromptu nurses. The Story of a WAAC is, however, a fictionalized memoir, its author anonymous, and so I felt the evidence it provided was unreliable. I did eventually discover several memoirs and contemporary accounts, mainly letters and diaries, that do mention the presence of WAACs in several clearing hospitals near the Front, so I felt safe enough in sending Lilly and her friends to the Fifty-first CCS, where their presence would have been unusual but not wholly improbable.

Fortunately there was no shortage of sources, both primary and secondary, on the experiences of First World War ambulance drivers. Not So Quiet: Stepdaughters of War, written by Helen Zenna Smith in 1930, presents the most vivid and compelling descriptions I have yet found of the life of an ambulance driver during the Great War. Though Not So Quiet is a novel, Smith based it on the actual war diaries of ambulance driver Winifred Young, and it shows. Here, the narrator describes her first night ferrying wounded soldiers from a railhead to a nearby hospital:

I drove til dawn to and fro—station, Number Five Hospital—Number Five Hospital, station…sick, numb, frozen-fingered, frozen-hearted…station, Number Five Hospital—Number Five Hospital, station…

It ended, just as I thought it would never end. Back again at the depot I collapsed with my head on the steering wheel [and] I whimpered like a puppy…I couldn’t go on…I was a coward…I couldn’t face those stretchers of moaning men again…men torn and bleeding and raving…

As I continued to research the work of ambulance drivers, I learned it was every bit as difficult, exhausting, unpleasant and emotionally draining as recounted by Helen Zenna Smith. The vehicles were difficult to drive and maintain, particularly so in cold or rainy weather. The routes the drivers traveled were exceptionally treacherous and the hours they worked were very long. Worst of all was the suffering of their passengers, to which they were witness day after day, night after night, month after soul-destroying month. Ernest Hemingway, himself a volunteer ambulance driver with the Red Cross, described it simply in a letter to his parents. “The ambulance is no slacker’s job.”

Through my portrayal of Lilly and her friends, I hope I have been able to shine some light on the contributions of the almost sixty thousand members of the WAAC and, in particular, the work of its ambulance drivers. It isn’t much by way of thanks, but I offer it wholeheartedly all the same.