Military Book Reviews

Britain’s Secret Defences: Civilian Saboteurs, Spies and Assassins During the Second World War

Britain’s Secret Defences: Civilian Saboteurs, Spies and Assassins During the Second World War by Andrew Chatterton (Casemate Publishers, 2022, 205p)

The narrative surrounding Britain’s anti-invasion forces has often centered on ‘Dad’s Army’-like characters running around with pitchforks, on unpreparedness and sense of inevitability of invasion and defeat. The truth, however, is very different.

Top-secret, highly trained and ruthless civilian volunteers were being recruited as early as the summer of 1940. Had the Germans attempted an invasion they would have been countered by saboteurs and guerrilla fighters emerging from secret bunkers, and monitored by swathes of spies and observers who would have passed details on via runners, wireless operators and ATS women in disguised bunkers.

The civilians involved in these groups understood the need for absolute secrecy and their commitment to keeping quiet meant that most went to their grave without ever telling anyone of their role, not even their closest family members. There has been no official and little public recognition of what these dedicated men and women were willing to do for their country in its hour of need, and after over 80 years of silence the time has come to highlight their remarkable role

Britain’s Secret Defences: Civilian Saboteurs, Spies and Assassins During the Second World War by Andrew Chatterton is an intriguing foray into super-secret guerrilla warfare plans developed by the British during World War II in anticipation of a German invasion. Early in the war, it became apparent that German forces intended to invade Britain. Several factions within the British government and military believed this invasion was inevitable. While leadership made plans to repel the Germans, others prepared for the worst.


The Secret Intelligence Service (SIS, later known as MI6), the Home Guard, and Military Intelligence units all created groups of civilians to train in guerrilla warfare in the event of occupation by German forces. Auxiliary Units were groups intimately familiar with local landscapes. They performed duties in the areas where they lived and worked. Many had prior military experience. Others were farmers, factory workers, and business owners. Volunteers for the Auxiliary Units swore to absolute secrecy, both of their participation in the units and the duties they would perform. Often, the leaders of these units recruited friends and family members based on the extreme need for secrecy.

Auxiliary Units trained in secret locations and taught tactics to disrupt the effectiveness of German occupying forces. They focused on disrupting transportation assets, such as roads, railways, and airfields. These units considered anything to sabotage the invaders as fair game. They trained their personnel to assassinate German officials and British collaborators and to be utterly ruthless in their defense of the British homeland. They also developed plans to kill British citizens who could reveal the identities of the members of these secret units.

The Auxiliary Units’ need for secrecy required them to hide their bases of operations. These Operational Bases (OBs) commonly were dug into the earth and well hidden. They were bunkers capable of holding several people and the supplies required to operate efficiently. Bunkers stored food, water, weapons, and other equipment. A full patrol often would have revolvers, rifles, fighting knives, grenades, other explosive and incendiary devices, sufficient ammunition, and possibly one or two machine guns. The training and use of explosives was a core component of the units. Destroying infrastructure and equipment that the invading forces might use against the British people was a key mission they prepared for.

As the war progressed and the threat of invasion diminished, the Auxiliary Units were forced to change their role or disband. While many transitioned to other roles and duties, the units changed with the times. They learned anti-raiding tactics to combat the threat of coastal raids. Fascinatingly, they also trained in royal protection duties. The royal family frequently stayed at Balmoral Castle in Scotland during the war, and the Auxiliary Units ensured their safety and protection during those times. Eventually, these operational units stood down as the war drew to a close.

There were other efforts occurring behind the scenes. Civilians filled positions as spies and wireless operators, and women served in the Auxiliary Territorial Services (ATS). Civilians, including women, filled many vital roles critical to homeland defense because of a shortage of military personnel.

The secrecy surrounding these Auxiliary Units was a fundamental component of their success. Few records now exist to document the inner workings of these organizations or the identities of those involved. Even after several books published information on the topic, many thought to be involved took their secrets to the grave.


This book provides a detailed overview of the steps the British people and their government took to ensure the integrity of their homeland during a national crisis. It shows the measures people will take to defend what is their own as well. It also highlights the pride and ownership that the civilian population took in supporting their nation. The book gives a good insight into guerrilla warfare tactics and concepts from the perspective of homeland defense. Individuals who are fans of military history or are in a position of leadership regarding homeland defense will find this book informative and interesting.

Matt Long is a contributing reviewer to DODReads.  He is an active-duty Naval officer and real estate investor.  An advocate for life-long learning, in his free time he can be found reading or hiking.  Matt can be reached through LinkedIn at

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