Derwent Mouth is a location on the River Trent, which at that point forms the border between the English counties of Derbyshire and Leicestershire.
The River Trent is navigable, with the aid of locks, downstream of Derwent Mouth as far as the Humber Estuary.
Bargees who had been ensnared by the frozen conditions attempted to protect the bridge by adding heavy loads, and by fending off the ice floes.
When the bridge finally gave way, James Thompson ended up afloat on the ice, and was washed downstream, but he later reached the riverbank unharmed.
[1] Rather than reinstate a similar bridge, it was decided to construct a wider multi-user crossing at a location some 140m upstream from Derwent Mouth.