Trench construction in World War I

When people think of World War I, one of the first images that comes to mind is the trench.  Here’s a look into how these major features were constructed, as well as their impact on the war.

1. When were the trenches in World War I first built?

French troops waiting assault behind a ditch during the Battle of the Marne.

After the Battle of the Marne in September 1914 (one month after the war truly began), the Germans were pushed back to the River Aisne.  The German commander, General Erich von Falkenhayn, assessed the situation.  Not wanting to lose the territory in France and Belgium Germany had gained, he ordered his army to dig trenches to defend against French and British troops.  The trenches provided necessary protection from artillery shells and machine guns, and gave soldiers a major advantage when warding off a frontal assault.  Realizing that they could not break through these trenches, the British and French soon began digging their own.

Over the next few months the equally-matched armies tried to outflank each other, continuously adding on to their trenches as they went.  This “race to the sea” ended with two parallel trench lines running from the North Sea all the way to the border of Switzerland.  If all of the trenches constructed during World War I were laid end to end, they would cover 25,000 miles.

Because the Germans dug in first, they were able to seize the high ground.  This not only gave them a tactical advantage, it also kept them much drier than the British and French, who were forced to dig in areas that were typically only 2 to 3 feet above sea level.  This led to frequent flooding and an almost constant presence of water in Allied trenches.

Trenches could sometimes flood as high as a man's waist.

2. How were the trenches constructed?

There were two main ways to dig a trench.  There was entrenchment, which was the faster method, allowing many soldiers equipped with shovels and picks to dig a large portion of trench at once.  However, this left the diggers exposed to all of the dangers that the trenches were supposed to protect against.  So entrenchment had to take place either in a rear area where diggers were not as vulnerable, or at night.  British guidelines for trench construction inform us that it took 450 men approximately 6 hours to dig 275 yards of a front-line trench (approx. 7 feet deep, 6 feet wide) a night.

The other option was sapping, where a trench was extended by digging at the end face.  It was a much safer route, but took more time, as only one or two men could fit in the area to dig.

These trenches were dug through the beautiful countryside of France, and often through private property, particularly that of farmers.  Private Victor Wheeler, a Canadian soldier, described his experience when digging one of the first Allied trenches:

With pick and shovel we dug trenches through beautiful fields of grain, fully realising what damage we were doing to the farmers’ hopes of reaping small harvests that would enable them to stem hunger during the coming winter. The patriarch with his ox-drawn plough, the matronly gleaner, and the young woman gathering grass and leaves, roots and truffles, stood arms akimbo, wordlessly, helplessly, hopelessly watching. The depressing effect on the morale of the men – to many of whom raising grain on the Western prairie also meant their livelihood – could not be easily dismissed.

After a trench was constructed, sandbags, wire mesh, and wooden frames would be brought in to reinforce the walls.  Wooden planking, referred to as duckboards, were also put in place to prevent men from standing in water, which often led to an ailment known as “trench foot.”  Shell fire and the weather made constant maintenance a necessity.


3. How were the trenches laid out? 

Trenches were never built in straight lines but instead in a zigzag pattern.  This method was used so that if the enemy invaded a trench, they would be prevented from firing down its entire length, as well as providing some buffer in the event a shell were to explode.

Multiple trenches were created on either side of No Man’s Land.  The front-line trench was exactly as it sounded–it was the first line of defense.  Sandbags placed at the opening of the trenches were particularly important here, as they also absorbed bullets that might otherwise hit soldiers.  Fire-steps were built into the sides and allowed soldiers to see over with their rifles at the ready when on sentry duty or when an enemy attack was anticipated.

Cross-section of front-line trench

Front-line trenches also had appendages called “saps,” which were dug out into No Man’s Land and used as listening posts to find out information about the enemy.

Behind the front-line trench was the support trench.  As its name implies, it held support troops and supplies to aid the front-line trench soldiers when necessary.  It also could be used as a fall back point if the enemy occupied the front-line trench.  Dugouts were typically built in the rear of the support trench, varying in size between 8 to 16 feet for the British.

Beyond the support trench was the reserve trench, which held emergency supplies and troops, in the event the first two failed.

All three of these trenches were connected by communication trenches, which allowed men and supplies to travel safely back and forth.  This is also where telephone lines could be run.

A soldier did not spend the allof his time in any given trench.  A typical British soldier spent 15% of his year on the front line, 10% on the support line, 30% on the reserve line, and the rest of his time would be spent either on rest, on leave, in the hospital, etc.

4. German trenches

Loos-Hulluch trench system

Unlike the British and French trenches, German trenches were much more elaborate in construction.  This was due to the defensive strategy of their army.  The above photograph is an excellent illustration of this: the German trenches are located to the right, the British to the left.

German bunkers were also more sophisticated.  Unlike the shallower dugouts of the British, German dugouts were typically 12 feet or more in depth, and were sometimes constructed three stories down, complete with concrete stairs.  German dugouts also typically had electricity, as well as toilets (luxuries that were not found in Allied trenches).

5. Significance

It soon became obvious to both sides that this would be a war of attrition.  Who could outlast the other with men and supplies?  Trench warfare created a stalemate that prolonged the conflict well past what either side originally imagined.  It would take the implementation of new tactics and technology to finally propel the war to its conclusion.

Sources: Spartacus Educational, Trench Warfare, St. Boniface’s College, 



Filed under World War I

15 responses to “Trench construction in World War I

  1. Pingback: Trench scenes in Downton Abbey | Diana Overbey

  2. Pingback: Life in the Trenches | Diana Overbey

  3. Antoine Vanner

    A good article and glad to see that you highlight the rotation of men thrugh duty in the trenches – in the British sectors troops spent less than a week at a time in the front line though of course this could be extended during critical periods. This is not the picture given in portrayal of the period in popular media. A lot of attention was paid by the British to morale issues, unlike in the French Army in which troops were so badly paid that some went to work temporarily in factories like Renault’s when they were on leave and in which callous treatment finally led to large-scale mutinies. An excellent book on this subject is Richard M.Watts’ “Dare Call It treason”..

    • Thanks so much for your comment Antoine! I’m glad you enjoyed the post. And thank you for the interesting information about the French troops and morale, I did not realize just how poorly paid they were. Thanks for stopping by my blog, and for the book recommendation!

  4. David Bean

    I’ve been reading Paul Fussell, and I gather from him that another reason for the discomfort and inferiority of the Allied trenches was the official position that the British would soon be on the attack and that, therefore, life in the trenches was only a temporary inconvenience. Soon, soon, they would be over the top, would break through the German lines and be on their way to the Rhine.

  5. Reblogged this on eamonntgardiner and commented:
    Great article here from Diana Overbey on the construction of trenches!

  6. April

    You’ve really helped a couple of my students with this post! They are doing a project on WWI and their focus is Trench Construction. They were overwhelmed by the other sites because they weren’t as concise. Great job!

  7. Pete

    Hi. Thanks for the great post. I’ve learned a lot.
    I have a question: would you know what the white alongside trenches is, as seen in the aerial view? Thanks!

    • Hi Pete! Glad you found the post informative.

      Unfortunately I’m not certain what the white portions are on the aerial shot. If I had to make a guess, I would say the white is likely bare earth, and the darker portions may be places where grass still grows. You can get a much closer view with this photo, which appears to show craters where shells have hit: The areas around the craters are the same white color, which is what leads me to think it’s bare earth. Hope that helps!

      • Paul

        I know this is a late reply but the white around the trenches is indeed the ‘bare earth’ as chalk is the underlying bedrock in the Somme downlands. (this made the job of listening to the counter-mining by the enemy much easier than in the Ypres sector – a ‘tunneller’ would find a forward pocket in the mine in which he was working and ‘polish’ a section of the chalk to place his listen device against. Just like putting a glass against a wall with your ear on the base – the sound vibrations would travel very clearly through the hard material.

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  9. Pingback: First Battle of Marne, Sept 5-9, 1914 – subratachak

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