Butler became the recognized leader of the Ladies National Association for Repeal of the Contagious Diseases Acts, the first major women-led political campaign in the UK.
By 1870, Josephine Butler had emerged as the leading figure of the Ladies National Association for the Repeal of the Contagious Diseases Acts (LNA), an organization formed in response to legislation that mandated invasive medical examinations of women suspected of prostitution in garrison and port towns, while leaving their male clients entirely unregulated.
Butler's leadership of the LNA is widely regarded by historians as the first large-scale, successful political campaign organized and led by women in British history. At a time when women could not vote, hold political office, or typically speak in public forums, Butler travelled the country delivering speeches to often hostile crowds, organized petitions signed by tens of thousands, and published pamphlets exposing the degrading and unconstitutional nature of the Acts' enforcement, including forced gynecological examinations that she likened to 'instrumental rape.'
Her leadership required extraordinary personal courage: she faced public vilification, threats of violence, and social ostracism for daring to discuss sexuality and prostitution openly as a respectable woman. Yet her moral authority, rhetorical skill, and unwavering conviction galvanized a nationwide coalition of women reformers, doctors, and sympathetic politicians. This campaign is considered a foundational moment for organized British feminism, establishing methods of women's political mobilization — petitioning, public speaking tours, and cross-class organizing — that would later underpin the suffrage movement.