He became interested in writing in 1984 when, as a career army officer, he authored a book and worked on a television documentary about New Zealand's involvement in the Gallipoli campaign. In 1987, he left his position of infantry lieutenant-colonel to dedicate himself to a new career as historian. In 1994, he became Writing Fellow at the Victoria University of Wellington. He then taught at University of New England, Australia from 1996 to 1999. He is currently Senior Lecturer in War Studies at the Royal Military Academy Sandhurst and Adjunct Senior Fellow at New Zealand's University of Canterbury.