Firefighters are to strike for four hours next week in a row over pensions, the Fire Brigades Union said.
Almost 80% voted in favour of industrial action in a ballot that ended earlier this month.
Union officials had left the strike to the last possible moment to allow for the possibility of a negotiated settlement.
The strike will take place next Wednesday, September 25.
Fire Brigades Union (FBU) general secretary Matt Wrack said: "This initial strike is a warning shot to Government. Firefighters could not be more serious about protecting public safety and ensuring fair pensions.
"Governments in Westminster and Cardiff have simply refused to see sense on these issues.
"It is ludicrous to expect firefighters to fight fires and rescue families in their late 50s: the lives of the general public and firefighters themselves will be endangered.
"None of us want a strike, but we cannot compromise on public and firefighter safety."
Firefighters in Scotland will not strike next week while union officials are discussing the Scottish Government's most recent proposals.
But as a settlement in Scotland has not yet been found, the union's strike ballot could still result in industrial action there too.
The walkout will take place for four hours, between noon and 4pm.
On Saturday the FBU said it expected a strike to be "unavoidable" following a meeting of its executive council.
The union said Government figures showed that thousands of firefighters could face the sack without access to a proper pension simply because they are getting older.
A recent Government review found that more than half of current firefighters between the ages of 50 and 54 are no longer able to meet fire and rescue service fitness standards for fighting fires, while two thirds of those beyond the age of 55 fail to meet the standards.
Although the Government has previously claimed that older firefighters could be moved to less physically demanding roles, the FBU said its research found only a handful of "redeployment" opportunities in fire and rescue services, meaning mass sackings would be inevitable.
Firefighters already pay some of the highest pension contributions in the UK public or private sector and have seen increases for two consecutive years, the union said.
The majority of firefighters already pay almost 13% of their salary in contributions with further increases due next year. This will mean some firefighters now face an increase six years in a row.
The FBU also argue that financial projections from the Government are flawed as they are based on a prediction of a 1% decline in pension sign-up when their own information suggests that more than 25% of full-time firefighters recruited last year chose not to join.