The Great Sheffield Flood was a disaster which devastated parts of Sheffield, England in 1864. The flood resulted in more deaths than any other in Britain before or since.

The flood occurred when the Dale Dyke Dam, under construction above Low Bradfield on the River Loxley burst. This sent huges waves of water flooding down the valley, through Loxley and Hillsborough, and then down the River Don through central Sheffield, Attercliffe and as far as Rotherham. The estimated seven hundred million gallons of water destroyed eight hundred houses, killing 270 people, and wrecking every bridge as far as the Lady’s Bridge in the city centre.