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The revolutionary Bailey Bridge has played an important role over the years – initially providing critical connections in the Second World War, but more recently in getting vital supplies to people across the globe, both in civilian and military applications.

The modular, rapidly deployable Bailey Bridge has its origins in the years before the Second World War, when civil servant Donald Bailey came up with the concept, producing his original sketch on the back of an envelope in 1936.

His idea was largely ignored at the time, but then war broke out. An upgraded version of the First World War Inglis Bridge failed, as the new and improved military vehicles were too heavy. So on 14 February 1941, Bailey received a letter from the War Department telling him to prepare for a full-scale trial of his bridge design in May that year at the Experimental Bridging Establishment at Christchurch, Dorset.

Successful trials meant the Bailey Bridge went into production in July 1941 and was issued to the army that December. British, Canadian, Australian and US engineers used the system – its rapid rollout showed just how progressive and easy to implement it was.

The Axis Powers didn’t have this kind of trick up their collective sleeve, so the bridge’s contribution to the war effort was vital. As Field Marshal Bernard Montgomery put it: “Bailey bridging made an immense contribution towards ending World War Two ... I could never have maintained the speed and tempo of forwarding movement without large supplies of Bailey bridging.

“Without the Bailey Bridge, we should not have won the war. It was the best thing in that line that we ever had.”

Ease of transporting hefty military hardware using the Modular Steel Bridge essentially won the war. For example, the Battle of Remagen, where Allied forces captured the Ludendorff Bridge over the Rhine and pretty much shortened the war in Europe, is where the Bailey Bridge fully flexed its muscles.

Pontoon Bridges were set up across the Rhine in Germany to aid the advance. The longest was called ‘Blackfriars Bridge’. It was 558m long and was built close to the Dutch border by the Royal Canadian Engineers of the 2nd Canadian Corps. After two days of construction – delays were due to heavy fog and hampered delivery of components – the floating section of the bridge was rated as Military Load Class 40; enough for 40-ton tanks to cross over safely.

The bridge used modular panel construction, so elements could be transported and assembled on site, according to the length needed. “At its peak, around 20,000 panels were produced each month during World War Two,” says Callum Skeat, military sales manager at Mabey Bridge, the company that took on and developed the Bailey Bridge. “Over the entire war, over 700,000 panels were produced; enough to stretch from London to Leningrad.”

It was light and quick to assemble – it usually took 24 hours – and was strong enough to carry the heaviest tanks over a 60m span.

“The simple deployment of the Steel Foot Bridge has not really changed since its first use in 1942,” says Skeat. “Original Bailey Bridges were built by hand and cantilevered [cantilevers, which are projecting beams or members supported at only one end, can hold a bridge up to 550m] over a gap using a light nose section dismantled on the far bank, and pushed out by rollers.”

The first span can be easily joined to other panels to form multiple spans. You just feed them across the gap on rollers until you have the bridge length you want.

So what made it so snazzy? Well, the First World War Inglis Bridge required building a bridge twice as long as you wanted, swinging it out over a gap on a pivot, and then you’d dismantle the bits of bridge you didn’t need. “This was a timely process, but the Bailey’s simple, robust and modular design meant it was infinitely more versatile and quicker to build. Plus, all parts could be assembled by hand, which was a revelation during the 1940s,” Skeat adds.