When William Booth met Catherine Mumford in 1852 it was the start of a love story that would change the lives of tens of thousands. Out of their love sprang a new and radical international Christian movement – The Salvation Army – which in 2015 celebrates its 150th anniversary. Throughout their life William and Catherine, when not together, wrote letters and notes expressing not only their deep love but also a lasting friendship and mutual respect which would survive the challenges of separation, ill health, the struggle of raising a large family, opposition, disappointment and professional uncertainty. In the letters Catherine and William exchanged almost from their first meeting in 1852 until Catherine’s death in 1890, are also the everyday minutiae of life in Victorian times, marriage, family, children and the challenges of being radical Christian thinkers in the second half of the 19th century.