* The Great War: A People's History (2014): This book tells the story of World War I from the perspective of ordinary people on all sides of the conflict.
* The First World War and the British People (2004): A comprehensive study of how the First World War affected British society.
* The Imperial Reckoning: The Untold Story of Britain's Gulag (2020): Wills explores the history of Britain's colonial prison camps, highlighting their brutality and impact on the lives of those incarcerated.
She has also written various articles and essays on topics related to the history of the British Empire and World War I.