Which novel introduced the fictional detective Father Brown in 1911?

The Innocence of Father Brown introduced G. K. Chesterton's detective Father Brown in 1911.

The book is a collection of short detective stories featuring a short, unassuming Roman Catholic priest. Father Brown solves crimes by understanding human weakness, guilt and temptation, rather than by displaying the theatrical brilliance associated with some earlier fictional detectives. His religious knowledge is an important part of his reasoning.

Chesterton published the collection in 1911. Stories such as “The Blue Cross” established Father Brown's distinctive method and introduced readers to a detective who could recognize criminal motives from moral and psychological insight. The character later appeared in four additional collections.

The title is sometimes confused with The Wisdom of Father Brown, which is the second collection, published in 1914. Father Brown is also sometimes treated as a conventional priest-detective mystery figure, but Chesterton used the stories to explore ethics, rationality, crime and the limits of material evidence.