Pontoon bridges are one of the oldest forms of military engineering in the world. In their simplest form, they consisted of a string of boats, lashed together with a walkway laid between them.
Although modern pontoon bridges have changed in design since those of antiquity, they are essentially the same. Modern pontoon bridges would likely be familiar to Ancient Chinese, Romans or Persian armies of antiquity.
But, of course, some things have changed:
-The materials used to build them,
-The manner of anchoring the pontoons,
-Improvements in load carrying capacity,
-Fast-moving current resistance,
In the following article, we'll take a quick tour through the history or pontoons bridges. We'll also, at times, go into a bit more detail on a few selected designs and battles.
The First Pontoon Bridges Built in Ancient China
It is believed that Ancient China was the birthplace of the pontoon bridge. Accounts from the text of the ancient book, Shi Jing, from the Zhou Dynasty, reveals that the first ever one was built in the 11th Century BC.
Although this early account is disputed by historians, like Joseph Needham, more reliable evidence does show that Chinese pontoon bridges were common throughout the 8th and 9th Centuries BC.
More permanent pontoon bridges were also built in China during the Qin Dynasty between 221 and 207 BC. Later, the Eastern Han Dynasty created a very large pontoon bridge across the Yellow River.
These kinds of bridges were also used during the Gongsun Shu rebellion in 33 AD. The rebels managed to build an enormous bridge across the Yangtze River. This was later destroyed by Han Forces by ramming it with ships.
Further accounts of pontoons bridges being built would extend well into the middle ages. Some of these are still in use today.
A great example is the Dongjin Bridge in Ghanzhou that was built during the Song Dynasty (960 to 1279 AD).
The Great Pontoon Bridges by the Persians, Greeks, and the Romans
Herodotus, the famous Greek writer, gave accounts of pontoon bridges in his seminal work, Histories. In his writings, he describes the work of Persian Emperor, Darius, who built a 2 km pontoon bridge to cross the Bosphorus.
Darius recruited a Greek engineer to build the bridge so he could pursue fleeing Scythian forces and place his army in a position to subdue Macedon from the Balkans.
Caligula is also thought to have built a 3.2 km pontoon bridge at Baiae in 37 AD. This is said to have been carefully planned stunt to mock a soothsayer who claimed:-
"no more chance of becoming emperor than of riding a horse across the Bay of Baiae"
This 'stunt' is said to have cost a massive sum of money at the time and was particularly unpopular among the populace. Pontoon bridges would become a standard piece of military engineering within the Roman army too.
Emperor Trajan and Emperor Marcus Aurelius would leave evidence of this by depicting the technology on their triumphal columns in Rome.
The Pontoon Bridges' decline during the Middle Ages
With the fall of Rome, pontoon bridges declined in use during the middle ages. Though they were still used alongside regular boats to span rivers during military campaigns.
They also served to link communities that lacked their resources to build permanent bridges. The earliest floating bridge recorded during this period spanned the Dniepr River built around 1115 AD.
This bridge was built near Vyshhorod in Kiev. Toward the end of the middle ages with battles like the Battle of Calliano and The Battle of Garigliano, pontoon bridges began to become popular as standard military engineering once again.
The Battle of Calliano - The Revival of the Pontoon Bridge
The Battle of Calliano in 1487 would reverse, in part, the decline of pontoon bridges through the middle ages.
Calliano, was a decisive battle between the Republic of Venice and the Archduchy of Austria. It was also known as the War of Rovereto.
Both forces, numbering only a few thousand, were separated by the river Adige. Advanced Venetian troops swam across the river and began building a floating pontoon bridge to provide the rest of the army access to the Austrian controlled forts, Castel Beseno and Castel Pietra.
The Venetian commander then led his forces across the Adige and laid siege to the forts. This was a bold strategy by the Venetians but ultimately doomed.
Counter attacks from Austrian forces would force the Venetians into a calamitous retreat. Their cavalry forced the fleeing infantry back onto their pontoon bridge, which subsequently collapsed, leading to hundreds of men drowning.
Venice's influence would begin to wane in the region after the disastrous battle which ultimately led to the War of the League of Cambrai between 1508 and 1509.
The Battle of Garigliano - How Spain Taught The Venetians
The Battle of Garigliano took place on the 29th of December 1503. A Spanish army under the command of Gonzalo Fernández de Córdoba soundly beat the French under the command of Ludovico II, Marquis of Saluzzo by cleverly using a pontoon bridge.
Midway through November of 1503, the two armies were separated by the Garigliano river, 60 km North of Naples. The engagement had become a stalemate with both forces camped in marshy and pretty unpleasant conditions.
The French, however, enjoyed good access to supplies from the nearby port of Gaeta. The Spanish would need to attack soon or retreat.
The Spanish army received reinforcements from Naples and decided to act immediately. De Córdoba devised a strategy to use boats and barrels as pontoons to build a makeshift bridge to get at the French and break the stalemate. The bridge was built in secret in the castle of Mondragone, around 12 km to the south of their position.
This bridge was brought up to the Spanish camp and deployed 6 km North of the French position under the cover of darkness between the 27th and 28th of December. With the bridge in place, Spanish forces crossed to the French side and launched a surprise attack that ultimately led to the decisive victory of the Spanish.
Pontoon Bridges Throughout the Modern Period
Throughout the 17th to 19th Centuries pontoon bridge technology underwent a kind of revival. Many nations around the world, once again, recognized the strategic and logistical value of them and began to develop their applications.
The French during the 1670's began developing the copper pontoon. This suddenly meant canals and rivers were no longer significant obstacles for their forces.
The battles of the 18th and 19th Centuries would also begin to become dominated by the use, at least in part, of pontoon bridges. Throughout this period the technology barely changed, but innovation did continue.
For instance, the Swedish Army, in 1708, managed to develop a leather pontoon bridge that they used in the build-up to the Battle of Holowczyn.
The British would make good use of so-called 'tin-pontoons' during the Peninsular War. These were prefabricated lightweight bridges that could quickly be deployed to provide a floating bridge.
The Battle of Oudenaarde - The Grand Alliance Used Pontoon Bridges to Defeat the French
The Battle of Oudenarde was a battle within the larger War of the Spanish Succession that took place on the 11th July 1708. The Grand Alliance of British, Prussian, Dutch, Danish and Austrian forces defeated similar in size French army using, in part, pontoon bridges.
With the threat of Spain and France joining forces, the Grand Alliance was formed against France and so began the War of Spanish Succession. Supreme Command of the Allied army fell to John Churchill, 1st Duke of Marlborough.
Churchill has around, 80,000 troops at his command and they were situated just south of Brussels. The French, with around 85,000 men, concentrated around Mons.
The French moved to take Bruges and Ghent and ultimately managed to control most of the Scheldt River. This left one British stronghold, Oudenaarde. If the French took this town Marlborough would be cut off from communicating with Britain - it had to be defended.
Using a series of pontoon bridges, Marlborough's forces were able to cross the river, take the battle to the enemy and ultimately routed them.
Pontoons Go From Open Boat To Cylinders and Back Again
During this period a significant effort was made to improve the design of pontoon bridges. It also led to a move away from the open boat type design of the pontoons.
This move was made as boats were hard to transport if there were no rivers nearby. They were also vulnerable to bad weather.
During the early 1800's a British engineer, Lt. Col. Charles Pasley, developed a new form of pontoon bridge for the British Army. The so-called Pasley Pontoon would be used by the British army until 1836 when it was replaced by the Blanshard Pontoon.
Both these types of pontoon were cylindrical with the latter having parabolic ends. The Blanshard pontoon would stay in service well into the 1870's.
The Pontoon Bridges of the 20th Century
By the end of the 19th Century, many other nations had continued to use open boat design and rejected the British closed forms. The British would soon follow suit and return to the boat design with The 'Blood Pontoon'.
This decision was made as cylindrical type pontoon became unstable when more than half submerged. These would prove highly successful and continued to be used right up to 1924 (Mk II).
This allowed the pontoons to double up as boats and be deployed as regular pontoons for bridges as and when required. These would prove to be very strong indeed and could support loaded elephants, siege guns, and even traction engines.
By the time of WW1, pontoon bridges would begin to see the development of trestles. These would be used to form links between a river bank and the bridge itself.
During the war-torn battlefields of WW1 infantry "pontoon" bridges would use anything to hand like petrol cans to act as floatation devices.
Both the British and American Armies developed another type of infantry pontoon bridge called the Kapok Assault Bridge around this time. These consisted of kapok filled canvas floats with timber foot walks.
The next biggest advancement would come in the form of the Folding Boat Equipment pontoon bridges (FBE). These were designed in 1928 and would go through a variety of versions until the Second World War.
There were specifically designed to provide a means of light vehicles over rivers to support assaults. The would take considerably less time to construct that Heavy Pontoon bridges but were less stable. They could also fold down completely flat making them very easy to carry and store.
The FBE Mk III would be extensively used throughout the war by the British and Americans. It was also widely used throughout the European and South-East Asian theatres of war.
The Iconic Bailey Bridge
The famous Bailey Bridge, named after its creator Donald Bailey, was a modular pontoon bridge used during WW2. It was a pre-fabricated steel trussed bridge that could cope with carrying as much as 40 tons over spans of 55 meters.
Although it was developed by the British it would be used extensively by Canadian and American military engineers too.
It could be built point to point using either piers or pontoons and was first used in 1942. A key feature of the Bailey Pontoon was the use of a single span from the bank to the bridge level which eliminated the need for bridge trestles.
The Bailey Bridge had the great advantage of not requiring specialized tools or heavy equipment to assemble. Its components were also relatively small and light enough to be carried in a truck and assembled by hand.
The Bailey Bridge would become the most iconic of the war and could be used as either a bridge or a raft.
Once assembled, these pontoon bridges were strong enough to carry tanks. They would be used long after the war for civil engineering construction projects and provided other means of temporary crossing for foot and vehicle traffic.
Post War Pontoon Bridges
Post World War II saw an abundance of raw materials and newly developed alloys that led to further developments in pontoon bridge designs. This would ultimately lead to the creation of the Light Assault Raft and Light Assault Floating Bridge (LAFB).
The LAFB would be the first military bridge to use hydraulic articulators. These were developed to carry all vehicles and equipment of an Infantry Division.
The LAFB's bigger brother the Heavy Assault Floating Bridge (HAFB) was introduced in the same period. But it wouldn't see active service until 1962. By this time amphibious bridging equipment was beginning to become more popular amongst military strategists.
Examples would be more versatile systems like the Class 80 Heavy Ferry and Mexeflote systems. The latter came into service in the 1960's and would prove to be very successful for many decades to come.
The Versatile Mexeflote That Can Form a Bridge, Raft or a Jetty
Mexeflotes were/are simple pontoon sections that could be pinned together to form lighterage rafts, jetties, and piers.
Multiple Mexeflotes can be combined and in addition to acting as a powered raft can also be as a jetty, floating transfer platform or other floating structures. The modular construction allows a variety of shapes to be constructed.
The versatility or Mexeflotes become obvious during Operation Corporate during the Falklands War of 1982. This operation was a huge logistical challenge with lines of communication stretching 8,000 miles from the UK to the far-flung islands.
It is estimated that the Mexeflotes offloaded some 75% of the stores and due to the weights being carried, especially ammunition pallets, the pontoons were often underwater.
Operation Badr 1973 - When Egypt Crossed the Suez
The Yom Kippur or Israeli-Arab, War of 1973 saw Egyptian forces make use of a pontoon bridge. Operation Badr, as it was known, was the Egyptian codename for their military operation to cross the Suez Canal.
It was timed to coincide with a Syrian assault on the Golan Heights. Egyptian combat engineers needed to use water cannons to clear passages through the sand wall lining the east bank of the canal.
The crossing was made with a mixture of pontoon bridges and ferries that allowed Egyptian armor to cross.
Although the action would initially take Israeli forces by surprise it would cost the Egyptian army heavy loses and would ultimately be a complete failure.
The Pontoon Bridge in Action Today and Beyond
More recently pontoon bridges have seen action in more recent combat arenas like the Yugoslav Wars of the 1990's. With the Meslenica Bridge destroyed a short pontoon bridge was built by Croatian civil and military authorities in 1993.
Between 1993 and 1995 this bridge was one of only two operational land links between Dalmatia and Croat and Bosnian Muslim held Bosnia-Herzegovina.
Prior to this Iranian forces used pontoon bridges to launch a daring night assault against Iraq during Operation Dawn 8 in the Iraq-Iran War in 1986.
Pontoon bridges also saw extensive use in the Invasion of Iraq by the U.S. 16 years later. The U.S. Army developed and deployed the Assault Float Ribbon Bridge to cross the Euphrates River in April of 2003.
The 185-meter long bridge was the first time in history a bridge of its type was built in combat.
Today military forces like the U.S. and British Armed Forces tend more towards Amphibious Regiments with pontoon bridges being a part of their arsenal.
Many modern forces make good use of the M3 Amphibious Rig. This is self-propelled amphibious bridging vehicle developed by EWK, since acquired by General Dynamics in Germany.
Like its predecessor the M2, the M3 traverses roads on its four wheels and deploys two large aluminum pontoons for buoyancy on water. Multiple rigs can then be connected to form a bridge across any water obstacle.
It would take about 8 M3's to bridge a 100-meter water course which can withstand the strain of a 60+ ton main battle tank.
Pontoon bridges have been info continuous use all over the world since their conception almost 3000 years ago. Though they have formed basic logistical functions throughout many wars they have also played pivotal roles in many battles throughout history.
Although their basic concept has changed little over that time their design and construction certainly have. Pontoon bridges look set to be an essential tool for military engineers for some time to come.