Educated at Mill Hill School in north London,[1] Mortimer's first book, the critically acclaimed Fields of Glory: the extraordinary lives of 16 warrior sportsmen was published in 2001 and described by the Sunday Telegraph as "inspiring reading".
Mortimer has subsequently written histories of the Special Boat Squadron, Merrill's Marauders and the Long Range Desert Group, drawing on interviews with the men who served in these Special Forces units.
He caused controversy in 2016 when he suggested that today's special forces lack the mental toughness of their forebears.
[5] Mortimer has acted as a consultant to several television documentaries including the three-part BBC series about the wartime SAS, which was broadcast in 2017.
[6] In addition to his military history, Mortimer has written several narrative non-fiction books, including The Great Swim,[7] about the race to become the first woman to swim the English Channel.