Bridges have a crucial role to play in conflict. They are important for supply networks and the movement of armies. But what about their defensive role? Many a bridge has been deliberately destroyed to prevent an enemy crossing a strategic river. Yet many bridges have survived wars, and some had fortifications incorporated into their structures.

The fortified gatehouse / tower or ‘bridge tower’ was a feature of pre-Medieval or Medieval times, and was used not only to guard an important crossing, but to collect tolls, which also helped pay for maintenance. These bridges were often part of the city or town walls. Even in more recent times towers were added into the design. (Think of Tower Bridge in London, which was built as part of the Gothic Revival and actually for commercial purposes.) Do any Medieval bridge towers remain in Britain? One does, it is the only one still in use. In Monmouth, Wales, on the River Wye, is the Monnow Bridge. So rare, the tower bridge is a Grade I listed building.

Why was there a fortified bridge at Monmouth? The Romans built a fort at a nearby settlement, but the river back then was crossed by a ford. It wasn’t until Medieval times that a Norman lord, who built Monmouth Castle, turned the town into an important defensive town.

In 1988, flood defences were added and the work uncovered wooden remains under the current bridge. The timber was dated using dendrochronology to around the mid-1100s. So this timber was probably part of the original wooden bridge. The stone bridge was added around a hundred years later. The Monnow Gate, the defensive tower, was incorporated another hundred or so years after that. The narrow arch had a portcullis and machicolations through which boiling oil or water was tipped.

Tolls were levied on all kinds of things to pay for the bridge, which has led to much debate among historians about whether the tower was there for defensive or monetary purposes. Since the tower wasn’t connected to any town walls, maybe collecting money was the chief purpose. In fact defensively, it wasn’t much use since, as the Romans did, the river could be crossed on foot upstream. Maybe the tower protected the those taking the levies from assault.

After the English Civil War, which it survived even though the town changes sides several times, the tower had an upgrade and was turned into a two storey dwelling for the gatekeeper. It also doubled up as a chapel, meeting room and lock-up (a small prison). Trade was now more important to the town, although occasionally the building was used to store gunpowder for the local military. In the 18th Century, rural gangs from opposing sides of the river fought around the gatehouse. Fights broke out, often in May, until banned in 1855, between “uptown” Monmouth youths and Overmonnow Cappers, who made the traditional Monmouth woollen cap. The usual weapon, which thankfully wasn’t boiling oil, but a sweeping broom (besom) reinforced with stones.

Formal protection of the bridge came in 1923, when it was designated an Ancient Monument. As for its legacy, we have many painters to thank for depictions through the ages, including Turner who sketched it in 1795.