The Inglis Bridge

This post has been updated and moved to HERE


Keeping with the current theme of the WWI commemoration I want to expand on an earlier post on WWI bridging, specifically looking at the Inglis Bridge.

That should actually read, Inglis Bridges, because there were several.

Most people tend to think of the Bailey Bridge as the first sectional military bridge but before the WWII Bailey Bridge, Charles Inglis designed the first dry gap prefabricated military bridge in service with any Army. A number of Stock Spans were introduced earlier but these were used in construction bridging rather than as a self-contained portable bridge.

One might not immediately envisage the trench warfare of WWI having a great deal of need for bridging, the majority of engineer tasks were fortification, infrastructure, tunnelling and the myriad of other duties that the Royal Engineers had, let’s not forget the Royal Engineers were the birthplace of the modern RAF, REME and Corps of Signals. When planning for the advance, several designs for lightweight transportable bridges were considered before those of Charles Inglis were selected.

Charles Edward Inglis (pronounced Ingles) was born in July 1875, after winning a scholarship to  Kings College Cambridge and spending time as a bridge design engineer he took up a lecturers post at Kings College in 1908. He would go on to a distinguished career spanning many decades, responsible for a wide variety of engineering innovation.

Charles Inglis
Charles Edward Inglis

But what of bridges and WWI?

In the early pre war period Charles Inglis was involved with the Royal Engineer section of University Officer Training Corps and started the preliminary design work on a portable infantry bridge but with the outbreak of war that had taken a back seat as he volunteered for service, appointed to an instructor post at the School of Military Engineering in Chatham.

By 1916 he was in charge of the Corps bridge design and procurement section.

From this point, Charles Inglis would design a number of important military bridges that would be in service until soon after WWII.

The Inglis Pyramid Bridge

The first Inglis bridge stemmed from his work carried out in 1913.

Officially called the Inglis Portable Military Bridge – Light Type it was generally known as the Inglis Pyramid Bridge.

As can be seen from the diagram below, the Warren trusses were angled in and secured with a single tubular top chord placed in compression. The bottom tubes were in tension and a number of trusses supported the single gangway.

Inglis portable Military Bridge - Light Type
Inglis portable Military Bridge – Light Type

Although the transoms were heavy at 198 pounds (90 kilograms) the tension tubes were very light and this, coupled with the simple construction technique, enabled a 108 foot long bridge to be completed in less than 15 minutes. Originally intended only for infantry and able to carry single file infantry over a 96 foot span it was actually possible to carry 3 ton vehicles by keeping the centres less than 16 feet apart and combining two bridge sets.

Inglis Light Type Double Span
Inglis Light Type Double Span

10 sets were ordered for use in France

Soon after the BEF requested a modified design that could carry first line transport vehicles.

Inglis responded by designing the Inglis Heavy Type Bridge

Instead of 8 foot tubes the Heavy type used 12 foot tubes and could carry loads up to 7 tons over a span of 96 feet. The tubes were fabricated at the Round Oak steelworks in Brierley Hill, West Midlands, which is now the site of the Merry Hill Shopping Centre.

17 Heavy Type Inglis Bridges were ordered and received into France in 1916 although they did not see widespread use because the triangular construction meant tall vehicles could not traffic the bridge.

A further modification was proposed that truncated the pyramid structure although this was not produced

Inglis portable Military Bridge - Light Type Modification
Inglis portable Military Bridge – Light Type Modification

There is only one Inglis pyramid bridge left anywhere in the world.

An Inglis Portable Military Bridge (Light Type) with the pyramidal construction is situated in Aldershot, just off Laffans Road near Browning Barracks. Laffan of course is familiar to any Sapper in the Hurrah for the CRE song, a former CRE. In WWII, Malta Barracks was on the edge of Laffans Road on the edge of Watts Common and was used for Royal Engineer training as well as the nearby Hawley Lake.

The bridge itself is between the Claycart and Farnborough Road bridges (AG and AH on the map above or see the Google map below)

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It is used as a pipe support although not sure what the pipe carries

This marvellous and historic piece of the nations military engineering heritage sits there alone and largely undocumented although the Basingstoke Canal Society do have some information on it.

The Inglis Bridge Mark I and Mark II

With the emergence of the tank it was clear that the existing stock spans and portable bridges would be unable to carry the vehicles. Now responsible for all military bridging in the British Expeditionary Force Charles Inglis was tasked by the Engineer in Chief to design an improved tubular bridge to carry heavier loads as typified by early tanks.

The resultant design took the tubular construction from the earlier Inglis pyramid bridges but used a more practical design with a lightweight pierced top web. The junction boxes were still cast iron and it used the same tubes as earlier designs.

Inglis Bridge Mark I
Inglis Bridge Mark I

The Inglis Mark I was able to traffic Class A loads (17 ton axle load) over gaps up to 96 feet wide using a 12 foot bay.

After arriving in late 1917 it was widely used in the final advance in 1918.

Chemin Vert Loop Line. Heavy Inglis type bridge carrying Bray-Chuignolles Road over River Somme at Bray
Chemin Vert Loop Line. Heavy Inglis type bridge carrying Bray-Chuignolles Road over River Somme at Bray. IWM
Bridging Company Royal Engineers constructing bridge over River Livenza alongside which had been destroyed by the Austrians
Bridging Company Royal Engineers constructing bridge over River Livenza alongside which had been destroyed by the Austrians. IWM
Inglis Mark II La Motte France 1918
Inglis Mark II La Motte France 1918

From Canada in the Great War

A number of standard-span portable bridges, varying in span from sixteen to eighty-five feet, were stored at the base depots. These bridges consisted of loose members and were bolted with machine-turned bolts. They were, however, very cumbersome, and this rendered their erection slow. The weight was another disadvantage, e.g. the eighty-five-foot span was a single-way bridge and weighed sixty-three tons.

Fortunately a new bridge, called the “Inglis Portable Military Bridge, Rectangular Type,” had been invented by Captain Inglis, R.E., and was adopted by the British Army. This bridge was the Warren girder type and was composed of a number of identical bays, each twelve feet long, twelve feet high, and twelve feet wide. It was designed to carry a dead load of eighty-four tons distributed over a clear span of eighty-four feet. Each part could be easily manhandled and the span could vary in multiples of twelve feet, e.g. sixty feet, seventy-two feet, eighty four feet, ninety- six feet, and one hundred and eight feet, to suit the gap. The bridge was built on blocks in skeleton form with a counterbalance arm and jacked up on to a two-wheeled trolley. It was then pushed over the gap, the counterbalance removed, then jacked down on the abutment, and the decking laid. On the 28th of September, 1918, a bridge of this type was erected complete over the Canal du Nord at Marquion in twelve and a half hours actual working time under severe shell-fire. A party of approximately two hundred sappers was employed on the construction of the bridge with the necessary approaches and abutments. The span was one hundred and eight feet clear and the safe distributed load fifty-one tons.

And here is a picture of them doing just that at the Canal du Nord in 1918

Canadian Engineers Canal du Nord Inglis Bridge MkI
Canadian Engineers Canal du Nord Inglis Bridge MkI

An Inglis Mark I was also used to span the Jordan River in Palestine, this being called the Allenby Bridge

Although a big step up in load carrying from earlier designs the unequal tube lengths could cause confusion during night builds and the new heavy tanks were still too heavy.

By the end of the War the Inglis Bridge Mark II was under trial, essentially a strengthened Mark I with 15 foot bays. A key improvement was a return to identical length tubes.

The Inglis Bridge was without a doubt the best military bridge of the time with short construction times and high carrying capacity but because it’s tubular steel construction, expensive.

After the Great War the Inglis Mk II continued to be used and developed into assault and floating bridges.

The Inglis Assault Bridge was a 135 foot long span with a pair of idler tracks. The concept called for the Royal Engineers Tank to use its jib to push the assembled bridge over the gap. In less than a minute a 70 foot gap could be bridged without exposing any personnel to fire, the first true assault bridge to use a bridge of substantial length, over the standard 30 foot assault bridges of the time.

Inglis Mark II Assault Bridge
Inglis Mark II Mobile Bridge

With the demise of the RE Tank (a modified Mark V** shown below) the Inglis Mk II Assault Bridge was not brought into service but the experience would inform later assault bridge designs.

The use of the Inglis Mark I and Mark II in floating bridge arrangements were also trialled in the immediate post war years.

The image above shows a Mark V** Female tank and Inglis Mk II pontoon bridge Experimental Bridging Establishment, Christchurch 1918.

Rafting a Mark V. Tank over a pontoon raft stiffened with Inglis Tubular Bridge. IWM
Rafting a Mark V. Tank over a pontoon raft stiffened with Inglis Tubular Bridge. IWM
Mark V. tank leaving a raft of pontoons with Inglis Tubular Frame
Mark V. tank leaving a raft of pontoons with Inglis Tubular Frame. IWM

The Imperial War Museum has an online video of Inglis pontoon and assault bridging at Christchurch in 1918

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After leaving the Army and returning to Cambridge after the war Charles Inglis continued his close association with military bridging, designing the Inglis Heavy Floating Bridge for example.

By the early thirties the Inglis Mark I and Mark II were out of service although they continued to be used for training and development and occasional use outside the UK such as the Barra Bridge in the Peshawer District India, in 1930

From the National Army Museum

Barra Bridge Peshawar

The ‘Inglis’ pattern bridge, named after its inventor, Lieutenant later Professor Sir, Charles Inglis, (1875-1952) was constructed across the Bara River by No. 4 Field Company, King George’s Own Bengal Sappers and Miners. The specifications required that it be capable of carrying infantry in fours or 10 ton steam rollers, one at a time. Work began on 29 October 1930 and the bridge was open for traffic on 23 November. Photograph from an album compiled by C G S Clarke, 1st King George’s Own Bengal Sappers and Miners, 1930-1931.

As with the Inglis Pyramid Bridge(s) there is only one Inglis Mark II bridge in existence, in Monmouth, over the River Monnow, built in 1931 to replace an old wooden bridge.

Recently closed to vehicle traffic it was maintained by the MoD because it marked the entrance to the headquarters of the Royal Monmouthsire Royal Engineers (Militia) at Vauxhall Field.

View Larger Map
The Royal Commission on the Ancient and Historical Monuments of Wales has a small image gallery for the Inglis Bridge at Monmouth, click here to view.

The Inglis Mark III Bridge

At the outbreak of WWII the Royal Engineers found themselves, like much of the British Army, without sufficient equipment for modern mobile armoured warfare and a widespread design effort was initiated.

Charles Inglis suggested a redesigned Mark II Inglis Bridge.

The Mark III Inglis Bridge was very similar to the Mark II but allowed the tubular trusses to be double or tripled up using a redesigned junction box. Top chords were not used.


Inglis Mk III General Arrangement
Inglis Mk III General Arrangement


Inglis Mk III
Inglis Mk III

The bay length was the same as the Mk I at 12 feet but as a result of this geometry, overhead bracing was not possible. After some controversy regarding the testing method used an order for one hundred 120 foot sets was placed but was soon eclipsed by the Bailey Bridge.

Inglis Mark III Under Test
Inglis Mark III Under Test
Royal Engineers constructing an Inglis Bridge Mk III at the School of Military Engineering, 18 June 1943
Royal Engineers constructing an Inglis Bridge Mk III at the School of Military Engineering, 18 June 1943. IWM

The Mark II did have one last hurrah as the Ingls Mobile Bridge although after extensive testing, it was not bought fully into service.

Inglis Mobile Bridge
Inglis Mobile Bridge

During this Period Charles Inglis also designed an improved crane system for building his bridges and a trestle for pontoon or floating bridges.

Inglis bridging crane
Inglis bridging crane


Professor Sir Charles Edward Inglis OBE died in April 1952, less than three weeks after his wife

The Journal of the Cambridge University Engineering Society 1952 has a very good obituary

Donald Bailey is rightly famous, but without the concepts developed by Charles Inglis we might not have seen the Bailey Bridge and for that, we owe him a great deal.



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Angus McLellan
Angus McLellan
February 23, 2014 10:00 pm

Thank you very much for this TD.

As I recall, Guy Hartcup’s exceedingly good The War of Invention: Scientific Developments 1914-1918 has great coverage of e.g. chemical warfare, explosive and communications. However, unlike his – to be honest, not nearly as good – Challenge of War: Scientific & Engineering Contributions to World War Two, it doesn’t cover bridging. [Presumably the clue is in the absence of the word “engineering” from the subtitle, silly old Angus. That’s a pity because as this article shows there are some fascinating byways to be wandered down.

In this area, can anyone suggest something to read about the pre-WWI German Pioneers’ “Rhine bridging train”? Preferably not in German, if at all possible!

Don Corrigan
Don Corrigan
February 24, 2014 1:54 am

Excellent historical info. There are several Bailey Bridges still in use around Hamilton Ontario. I remember seeing an Inglis Mark 1 in service at a pulp and paper mill in Northern Ontario in the early 70s

Deja Vu
Deja Vu
March 1, 2014 2:34 pm

Great article, I remember the bridge over the River Monnow from my Lt to Capt exam.

Driving this morning past the housing development of what used to be the Mill Hill Barracks in London, I note the road in is called Inglis Road.

March 14, 2014 7:25 pm

We do have sir Inglis designed bridge in Pakistan. Great work indeed by a great man. we are in a process to dismantle and launching it at some other place. Since to old version bridge i am in need of some dismantle and relaunching drills for it. Please help me getting some video or book on INGLIS BRIDGE. Your valuable help is solicited

March 17, 2014 6:01 pm
Reply to  Think Defence

Thanks for your valuable advise. yes i do have pictures of this bridge. you can send me email address for these pics if required.

Deja Vu
Deja Vu
March 19, 2014 6:55 pm

Sorry it is Inglis Way not Inglis Road in Mill Hill

Of course Inglis Way on the old Mill Hill Depot site could be named for the CO of The 57th (West Middlesex) Regiment of Foot at The Battle of Albuhera, Col (later Gen) William Inglis. Just found him as I trawled Wikipedia.

Col Inglis was hit by a 4 lb missile which enterd his neck and lodged in his back. He encouraged his men by shouting “Die hard the 57th, die hard!”

The casualties of the 57th were 422 out of the 570 men in the ranks and 20 out of the 30 officers. The Allied commander of the Anglo-Portuguese force Field Marshal Beresford wrote in his dispatch, “our dead, particularly the 57th Regiment, were lying as they fought in the ranks, every wound in front”

Inglis survived his wounds.

Makes one feel humble.

John Ellis
John Ellis
May 10, 2014 10:54 am

Can you assist with a query. Our local South Devon Royal Engineer Territorials were reported in pre war 1914 to be carrying our drills at the ‘Bridging Ground’ a site I have yet to identify. They were said to be training on the construction/erection of a bridge as below. Can you advise what type of bridge this might have been, as it appears that it might have been too early to have been an Inglis Bridge.
Thank you
John Ellis.

Extracted from the Mid Devon Advertiser 4th July 1914 – P5: BRIDGE BUILDING – The sixty foot span suspension bridge for infantry in file, which is being built by No. 1 Company Devon Fortress Royal Engineers, was proceeded with on Saturday, when the cables were put across. The fixing of the stays and supports entails a considerable amount of manual labour.

May 10, 2014 11:29 am

JE – after a 15 minute rummage in the Googlespace photo heap I found this: comment image – what a surprise TD had already covered it. The post is here: