U.S. Army, 1974-1980, BA&MA Economics, Economist for over 30 years for State of
California, Community College Adjunct Faculty
Tunnel warfare refers to the use of man-made or natural tunnels and underground cavities for military
purposes such as to undermine enemy fortifications, for surprise attacks, create ambushes, to
counterattack, to transfer troops from one portion of the battleground to another unseen and protected
and for shelter from enemy attack.
Early Tunnel Warfare
Accounts of tunnel warfare date back to mining and counter mining at the Roman siege of Ambracia in
189 BC. Philip V of Macedon used siege-mining in his siege of Prinassos in 201 BC.
Tunnels and trenches were also used for guerrilla warfare against the Romans. Hidden trenches were
used to assemble for surprise attacks along with tunnels to facilitate a safe fallback. Using tunnels was a
common practice of the Jewish rebels during the Bar Kokhba revolt (132–136 AD).
In the Middle Ages tunnels were dug under castles and fortifications to provide access or to collapse the
walls. The advent of gunpowder in tunnel warfare in 15th century was a turning point. Ivan the Terrible took
Kazan with the use of gunpowder explosions to undermine its walls.
Sébastien Le Prestre de Vauban (1633 –1707) the creator of the French School of Fortification gave a
theory of mine attack and how to calculate various saps and the amount of gunpowder needed for
In the Siege of Sevastopol (1854–1855) during the Crimean War the Russians dug 4 miles of saps and
counter mines to explode 12 tons of gunpowder while the allies detonated 64 tons with just under 1
mile of tunnels.
In the American Civil War in 1863 Union troops commanded by General Ulysses S. Grant tunnelled under
the Confederate trenches during the Siege of Vicksburg to detonate a mine. Another mine with
8,000 pounds of gunpowder was exploded in 1864 by Union forces during the Siege of Petersburg.
World War I
The Germans were the first to use tunneling to breach the enemy’s trenches. In December 1914, they
tunneled under and detonated ten mines that blew up an entire Indian brigade. To counter this threat,
Britain and France began forming their own tunneling forces. Britain started the war with no mining
specialist, but by the end of the year it had established brigade mining sections, although they had no
experience, tools or listening equipment. Starting in early 1915, these units were augmented with special
tunneling units made up of coal miners and sewer construction workers. In many cases, miners
were pulled from the middle of their initial basic training and sent straight to tunneling projects.
Tunnelers were considered elite specialists with valuable technical skills. While, they were kitted out
like regular soldiers and organized into Royal Engineer units, they were not treated as typical British
soldiers. They were paid 6 shillings a day compared to the standard 1 shilling a day. They often were
not subjected to the same rigid discipline that other soldiers experienced. Minor infractions often went
unpunished. Due to the confined working conditions and the lower troop-to-officer ratio, tunneling
officers often had more cordial relationships with their men than in the rest of the army.
By 1917 British and French tunnelers were superior to their German counterparts. They adopted
sophisticated listening devices (the geophone), silent air and water pumps, safer and more stable
explosives (ammonal) in place of gun powder and gun cotton. They also used compressed oxygen
breathing devices to protect tunnelers from foul air and fatal fumes.
In addition to the normal mining hazards like, toxic gasses, explosions and collapses, WWI tunneling
took place below no-man’s-land—a combat zone. Counter mining was tunneling to find and destroy the
other side’s tunnels. Diggers tried to work in silence and were constantly listening for enemy digging. If
enemy tunneling was detected, a “camouflet” or small explosive charge, was set off to collapse the
enemy tunnel while hopefully not collapsing your own. In some cases enemy tunneling ran into each
other which resulted in subterranean hand-to-hand combat.
The starting point of tunnels had to be concealed from the enemy. The detection of a tunnel would
invite deadly shelling. The excavated dirt also had to be surreptitiously removed from the digging site.
The constant German shelling also meant that off-duty tunnelers usually were in more danger while in
transit to their rest billets than while digging.
The Battle of Messines
The most successful and spectacular use of combat tunnels and mines in WWI was the assault on
Messines Ridge on 7–14 June 1917. This was a prelude to the Battle of Passchendaele (AKA the Third
Battle of Ypres) in 1917. The ridge dominated British positions south of Ypres. The objective was to
capture the ridge which would deprive the Germans of the high ground give the British control of the
ground on the southern flank of the Ypres Salient.
In September 1915 Brigadier General George Fowke, the BEF Engineer-in-Chief proposed deep digging
to build galleries 60 to 90 feet underground, much deeper than the 15 to 20 feet depth tunneled up to
that point. Work began on 21 tunnels in early 1916, a full year before the planned attack. The Royal
Engineer coordinated the tunnel digging by the British 171st, 175th and 250th Tunnelling companies and
the 1st Canadian, 3rd Canadian and 1st Australian Tunnelling companies
Digging work went on 24 hours a day with the tunnelers working 8 hours on and 12 hours off each day.
After four days, each section was relieved for 4 days of rest behind the lines, whereupon they were
given a ration of rum. However, because of the constant shelling, there were often more casualties on
the trip to and from the rear than in the tunnels.
The tunneling sections were divided into 8-man crews. Four men would dig while the other four hauled
out bags of the excavated clay. Progress accelerated when the clay kicking technique was introduced by
cockney navies who had dug tunnels for the London Underground. Before clay kicking, tunnels
advanced about 6 feet per shift. Afterward, they progress 12 to 14 feet per shift.
“To be a good clay-kicker you had to be long-legged, young and strong. At the age of twenty-one
I was all three. You lay on a wooden cross made out of a plank with the cross-strut just behind
your shoulders. The cross was wedged into the tunnel so that you were lying at an angle of forty-
five degrees with your feet towards the face. You worked with a sharp-pointed spade with a
foot-rest on either side above the blade, and you drove the blade into the clay, kicked the clay
out, and on to another section, moving forward all the time. With the old broad-bladed pick we
could only get forward at best six feet on every shift, but when the clay-kicking method was
introduced we were advancing as much as twelve feet, or even fourteen, on a shift.”
- Corporal T Newell, No. 12096, 171 Tunnelling Coy., Royal Engineers
At one point a motorized boring machine was developed and put to work. Initially it dug 3 times faster
than the men. But before long it was plagued with problems. When it was shut off to prevent
overheating, the digging head became stuck which required a day’s work for the men to free it. The
electricity generators which powered it didn’t produce consistent power, so fuses blew constantly. After
digging only 200 feet, it and its tunnel were abandoned where it still sits 80 feet underground.
When a tunnel reached a spot below a target, a large chamber was excavated. It was packed with
ammonal explosives (an explosive containing ammonium nitrate, trinitrotoluene, and powdered
aluminum) and the charging wires were set and strung back the tunnel opening. Yards of the tunnel
leading back from the chamber were backfilled with sandbags so as to direct the force of the blast up to
German positions. By early 1917, five miles of tunnels containing 19 mines had been completed.
Throughout the tunneling the Germans were actively countermining. The British diverted the attention
of German miners from their deep tunnelling with many minor underground attacks at shallower
depths. Although some tunnels were lost and restarted for various reasons, the German counter mines
and listening operations did not detect the deep British tunnels. In late April 1917 the commander of
German mining operations reported that German forces on Messines were safe from large scale mine-
explosions. The British tunnelling was one of the best kept secrets of WWI.
The work was completed in early 1917. Five miles of tunnels had been dug and 26 mines had been
packed with 454 tons of ammonal and gun cotton.
Nineteen mines under Messines Ridge were detonated at 3:17am on June 7, 1917. The explosion was
one of the largest non-nuclear explosions in history and may have been the loudest man-made noise in
history. It reportedly could be heard as far away as London and Dublin. It killed approximately 10,000
The explosion was followed by a creeping barrage and an attack by nine infantry divisions, about
80,000 British troops. The defending Germans were stunned and the British quickly advanced between
the gaps in the German line. The forward German line was overrun in half an hour. The British continued
to advance and captured the village of Messines by 7:00am and the entire ridge by 3:00pm. They
continued down the reverse slope of the ridge, dug in and withstood German counterattacks. The
victory at Messines was heralded as the most successful local British operation of WWI at the time. But
it did not lead to a breakthrough nor change the course of the war itself. Some of the most brutal fighting
of the war would be suffered during the subsequent Battle of Passchendaele. However, the specter of
British mines haunted the Germans through the rest of the war and they later cited tunneling
as one of the leading causes of their loss of the war overall.
Western Front underground activity peaked in June 1916. Britain exploded over 100 mines or
camouflets while Germany fired over 120; an average of one detonation every three hours. Britain
detonated the last mine of WWI on 10 August 1917.
After World War I
In World War II, Japan defended various islands in the Pacific—Peleliu, Tarawa, Iwo Jima—with
extensive tunnel emplacements rather than defending beaches. This tactic allowed tactical surprises
that greatly increased US Marine casualties who were forced to fight and flush out the Japanese on cave
at a time.
In the Korean War, North Korea used underground structures to defend against US air strikes. North
Koreans dug over 300 miles of tunnels
During the Viet Nam war Communist forces used underground bases to supply guerilla forces and
facilitate hit-and-run attacks. The US used volunteer combat engineers—Tunnel Rats—to destroy
tunnels, gather intelligence and to kill or capture tunnel occupants. This often required close combat
within the tunnels.
Both the Soviets and the U.S. fought Afghan guerillas in underground bases and tunnels such as those at
During the Siege of Sarajevo in 1992-1995, the Sarajevo Tunnel was built to link Sarajevo with the
Bosnian-held territory on the other side of the Sarajevo Airport to bring in food, military supplies
including weapons, and humanitarian aid.
Tunnels were used in recent Arab-Israeli conflicts to infiltrate fighters into Israel or to facilitate rocket
Syrian rebels dug tunnels to plant explosives under Syrian armed forces military positions during
the Syrian civil war (2011-2019).
Lyn MacDonald. Passchendaele 1917. 1978. Penguin Books
I.P. Willmott. World War I. 2003. Dorling Kindersley Publishing
Wikipedia articles: Tunnel warfare, Battle of Messines (1917), Mines in the Battle of Messines (1917),
Ammonal, Largest artificial non-nuclear explosions, Tunnel rat, Tunnelling companies of the Royal