Huge swathes of the North of England, including parts of Manchester and Leeds and their satellite towns, were under up to 6ft of water after a month's rain fell in a single day.
Thousands of residents were forced to flee their homes and in some cases whole towns were cut off as the misery of flooding spread across Lancashire, Greater Manchester and Yorkshire, and parts of Scotland and North Wales. And for the first time since the waters started rising a month ago, densely populated urban areas were engulfed.
It came after a day of extraordinary scenes when rivers and waterways broke their banks and continued downpours caused flooding on already saturated ground.
Earlier, rescuers on an inflatable dinghy pulled an elderly man from the sunroof of his Land Rover, which drifted through the Yorkshire town of Mytholmroyd almost completely submerged. He was said to be "seconds from drowning" when saved.
As Ministers spoke of unprecedented rainfall, people in the worst hit areas were urged to "flee for their lives". Flood alerts were issued across Greater Manchester where police chiefs told residents to "protect your property by elevating valuable and sentimental items".
In other developments:
•Environment Secretary Liz Truss abandoned her Christmas celebrations to visit the affected zone.•The Met Office issued two severe weather warnings, meaning danger to life, for further rainfall.
•Thousands of homes were left without power, with engineers frantically working to restore supplies.
•Hundreds of families in Lancashire and Yorkshire were rescued from waist-high water by soldiers and emergency crews in dinghies.
•A fire broke out on the banks of Irwell in nearby Radcliffe, Bury, after the swollen river dislodged a gas pipe causing an explosion.
•Rain caused a 20ft sinkhole to open up on the M62 near Rochdale. In one of the most shocking incidents the flooding destroyed a 200-year-old pub which sits on a bridge over the River Irwell at Summerseat, Greater Manchester.
