Annie Heloise Abel was born in England, and her family emigrated to the USA in 1884, settling in Kansas. She became one of the foremost women historians of the early 20th century and an authority on British and American policy toward Native Americans. Her doctoral dissertation at Yale, "The History of Events Resulting in Indian Consolidation West of the Mississippi," won the American Historical Association's Justin Winsor Prize in 1906 and was published later that year. Her most important work is considered to be the three-volume history of the American Civil War period known collectively as The Slave Holding Indians, consisting of The American Indian as Slaveholder and Secessionist: An Omitted Chapter in the Diplomatic History of the of the Southern Confederacy (1915), The American Indian as Participant in the Civil War (1919), and The American Indian Under Reconstruction (1925). She also studied British policy toward natives throughout the British Empire, not just in the Americas. Her other notable works included A Side-Light on Anglo-American Relations, 1839-1858. In 1921, she married George Cockburn Henderson, an Australian, and was known as Annie Heloise Abel-Henderson, although the marriage was short-lived.