Starting in the mid 14^th century, a major climatic change commonly referred to as the Little Ice Age began to take hold. Northern Europe felt the effects in the form of deep freezing temperatures and much heavier snowfalls than normal. The changes became great enough that major rivers began to freeze over during the winter months to a depth of up to three feet.

In England, the colder temperatures helped the lower sections of the Thames River to freeze over completely. But it was more than only climatic changes that caused the river to freeze. Structural changes along and over the river also profoundly altered the flow of the river.

London Bridge

Of all the physical elements that helped the Thames to freeze over, London Bridge helped the most. Constructed from 1176 to 1209, the bridge acted primarily as a defensive barrier against Viking and other invasions that had used the Thames as an easy avenue to sack the city of London. The bridge was constructed of many small stone arches and was maintained by collecting rent from homes, shops, and even a church built on the bridge.

Starlings were erected around bridge supports to act as defensive bulwarks against debris and ship collisions. But they also further restricted the flow of water under the bridge. Water flowed upstream and downstream depending on changes in the tide, and the elevation difference on either side of the bridge could be as much as two feet. Movement of water under the bridge was greatly restricted, especially in the event that a flowing ice sheet would become lodged between two bridge starlings, damming up the river even further.

Thus the salinity of the river was affect upstream of the bridge, since seawater could not easily flow upstream during tides. A lower water salinity combined with much colder temperatures during this time in history caused the River Thames to freeze over much more easily, about once every ten years.

Caution at First

The Thames froze over several winters but Londoners did not venture out onto the ice during these early years. In 1536 King Henry VIII traveled from central London to Greenwich by sleigh along the river. His people lined the river to get a glimpse of their king. Queen Elizabeth, Henry’s daughter, took to the ice frequently during 1564 for archery practice. It was after this that it is recorded that young boys would play games of football on the ice. Ice skaters glided up and down the river on newly invented iron skates, imported from Holland.

The frozen river was an economic disaster for those who operated fairies across the river. Their incomes temporarily frozen along with the river, the owners decided to put up tents on the ice to sell whatever they could to those crossing the now frozen river on foot. This is the start of what would eventually be known as a Frost Fair. From then on, shops would be set up on the river as soon as it froze over.

The first recorded frost fair was in 1608. One of the biggest frost fairs occurred in the winter of 1683–84 and was described by John Evelyn:

The Last Frost Fair

On December 26^th 1813, an enormous fog began to roll into London. The fog was more dense than anyone alive had ever seen. People who had lived in London their whole lives could barely find their way around the city. Coachmen dismounted from their horses and led them through the streets out of fear of colliding with something they might not be able to see from more than a few feet away.

Two weeks later the snow came. For days a heavy snow fell over southern England. The fog still lingered to some extent, made worse by Londoners burning coal to survive the intense cold. The Thames River quickly froze over. Some were brave enough to immediately venture out onto the ice, but most would not. On February 1^st an elephant was led across the frozen river just upstream of London Bridge to show the public that the ice was safe. The stage was set for one of the greatest frost fairs of all time.

Thousands of Londoners flocked onto the ice and erected what was essentially a whole new city. Winding streets were lined with all kinds of shops and restaurants, taverns and play stages. Printing presses were set up on the ice which sold souvenirs of the event. Shops were set up in tents or wooden structures. Rent was free since obviously no one owned the location they had built upon. Games were played, plays were performed, and horse drawn sleighs traveled up and down the frozen river.

London Bridge is Falling Down

Environmental changes as well as structural changes along and across the Thames altered the flow of the river enough that 1814 would be the last year of the frost fair. For over 600 years London Bridge had been the primary crossing point of the Thames in London. Its shops, residences, and its church had been an iconic part of the city.

By the beginning of the 19^th century the bridge was showing signs of major structural issues. Although the buildings on top had been demolished, it was still too narrow of a crossing for the amount of traffic it was now servicing, and the arches supporting it were a hindrance for the ship traffic below.

It was therefore decided in 1799 that a new bridge would be built as a replacement. The new bridge was built 100 feet upstream of London Bridge to minimize traffic disruptions, allowing the Medieval bridge to function until 1831, when it was finally torn down.

The supports of the new bridge allowed water to flow more freely underneath, altering the salinity of the lower Thames, making it far less likely to freeze over in the way it had for so many winters over the past 300 years. The great Frost Fair of 1814 was to be the last.

Originally published December 8, 2018

Sources:
  Famous Frosts and Frost Fairs in Great Britain by William Andrews
  Little Ice Age by Encyclopedia Britannica
  Remains of the old London Bridge by Historic UK
  Printed ‘Frost Fair’ Ephemera by Cambridge University Library Special Collections