Soldiers have been helping rescue services reach people trapped by heavy snowfall. Storm Emma slammed both countries after another winter storm that originated in Russia hit earlier in the week.
Britain called in the army on Friday after some of the most severe winter storms in recent memory battered the British Isles.
Storm Emma forced many roads and airports to close as it unleashed fresh snow and subzero temperatures onto southern Britain and Ireland.
Many areas were already reeling from fierce Siberian winds known as "The Beast from the East" that had hit both countries earlier in the week.
The British army transported first responders and also helped rescue drivers stranded in the snow. "The Armed Forces are assisting emergency services in ensuring essential NHS [Britain's national health service] staff are able to get to work and carry out their work in local communities," the Ministry of Defence said.
In the northeast of England, a woman gave birth on the side of a road after heavy snow forced her husband to pull over on the way to a local hospital.
“The weather was very bad and I struggled to find somewhere to pull over and barely had time to ring 999 when the baby started coming," Andrew Waring said. "I opened the passenger door and knelt in the snow to deliver the baby."
An ambulance crew found the family shortly after the birth and transported them to the hospital, where medical staff have been monitoring the baby.
"The baby had arrived shortly before we arrived so the hard work had been done," ambulance crewman Philip O'Donnell said, adding: "It was a lovely job to be involved in and we'd like to congratulate them on the new arrival."
Elsewhere, flights were canceled, schools shut and train services disrupted. Britain's national weather service, the Met Office, issued multiple alerts warning of snow, winds and cold temperatures.
In Ireland, a power outage cut electricity to some 24,000 buildings and forced schools throughout the country to close. Dublin airport also canceled all outbound flights.
The country's meteorological service, Met Éireann, kept a red weather alert in place for Friday, warning of continuing snowfall across the southern provinces of Munster and Leinster.
Read more: Rome sees first snowfall in years