Thanks to 'Dad's Army', Britain's Home Guard is well known. But far fewer people are aware of a shadowy army of trained resistance fighters whose role in the event of invasion was to disappear, and for two weeks (their anticipated life span) create havoc behind German lines.

In the dangerous summer months of 1940 invasion was a real possibility, and the army – desperately short of equipment after Dunkirk – would have had a tough time.

Furthermore, the newly formed Home Guard (or Local Defence Volunteers) at this point had no uniforms, little training, few rifles and hardly any ammunition.

Under the innocent-sounding name of 'Auxiliary Units', 4,500 men were secretly recruited and trained in sabotage, explosives, silent killing and firearms.

Hundreds of underground bases ('Operational Bases') were dug in great secrecy, their existence only known to the seven-man patrols who were supposed to occupy them. They were generously stocked with weapons and explosives.

Recruits were drawn from people with knowledge of the countryside and at ease with stealthy movement under cover. Farmers, gamekeepers (and poachers!) were ideal.

They were expected to be totally ruthless, because they were expected not only to sabotage German ammunition dumps and communications, but also to assassinate officers and even prominent local people who collaborated.

They were instructed to tell no-one of their role, and even if they were also members of the Home Guard they were under orders to disappear into their hideaways as soon as the Germans appeared and to emerge once the fighting had stopped.

Their bases had enough supplies for two weeks, and this was about how long they were expected to survive. Sooner or later the Germans would track them down, and in this event they were supposed to shoot each other or themselves to avoid capture and torture.

Civilians were also recruited to the Special Duties (SD) branch, whose role was long-term spying, observation and secret communications. The more short-term role of the Auxiliary Units was to cause significant disruption of German forces while British Army units regrouped for counter-attacks.

There is little doubt that these 'stay behind' units would have been effective, and their training was provided by unconventional officers steeped in the knowledge gained from the Spanish Civil War and the IRA in Ireland.

There were 34 patrols in Essex, each with six to eight men.

Maldon's patrol had its base in Beeleigh Mill, accessed through a trapdoor in the floor. It had seven members:

Sergeant John ('Jack') Smith, a butcher and owner of The Sausage King of Maldon, Market Hill.

Corporal Philip Hugh Markham, owner of Markham's Aerated Waters, Spital Road

Private William Robert Broome, Cowman

Private Horace William Nightingale, sheet metal fitter

Private Thomas Ewers Quilter, wharf foreman

Private George Frederick Rose, mineral water salesman

Private Edward Frederick Varley, Farmer.

Other patrols were based at Danbury, Wickham Bishops, Bicknacre, Purleigh and Hatfield Peverel.

The Dengie Peninsula had patrols at Latchingdon, Mayland, Southminster, Burnham on Crouch and Dengie village.

After the war, most hideouts were filled in and their weapons and explosives recovered. However, some were never discovered, and arms caches may still be out there. Derek Johnson's book 'East Anglia at War' recounts that farmer Reginald Sennitt of the Dengie patrols didn't surrender his weapons until 1964.

The marshy conditions meant that the unstable explosives were best stored above ground, and he moved them to his milk shed (after a spell in which they had occupied his bedroom). As other patrols were disbanded they handed their caches to him, but having signed the Official Secrets Act he felt it was best not to tell anyone and to wait for the army to collect them.

They never came, and when in 1964 he told the local police, he was in possession of 14,000 rounds of ammunition, 1,200 lb of gelignite, 310 paraffin bombs, 10 phosphorus grenades, 900 ft of fuse cord, and nearly 5,000 fuses, delay switches and booby-trap devices!

If we think times are tough, spare a thought for a time when ordinary people willingly volunteered for a suicide mission, abandoning friends and family, and contemplating having to shoot people they knew as well as the enemy.

Much of the history of the Auxiliary Patrols remains hidden, and if any readers have pictures or anecdotes on local personnel and their activities the British Resistance Archive always welcomes information. Their website can be found here.