Firefighters across England and Wales are due to strike in a bitter row over pensions.
Members of the Fire Brigades Union (FBU) will walk out for four hours from noon, the first national stoppage for a decade.
The union is campaigning against changes it says will mean firefighters will have to work longer, pay more into their pensions and receive less in retirement. The move will also see firefighters having to work on frontline duties until they are 60, the union argued.
The Government maintained that the changes were fair and would still give firemen and women decent pensions when they retire.
Fire brigades have drawn up their own contingency plans to deal with the strike because military Green Goddess machines, which have been used as cover in previous disputes, are no longer available. They have been sold by the Ministry of Defence to countries including Malta.
Some brigades, such as London and Surrey, are hiring private contractors to stand in for striking firefighters, but the public has been warned that some non-emergency calls will not be answered.
The London brigade, which is using 27 fire engines during the period of the strike, said calls about flooding, trapped animals and rubbish fires will not be answered.
Almost 80% of FBU members voted in favour of industrial action in a ballot that ended earlier this month, although union officials said they left the strike to the last possible moment to allow for the possibility of a negotiated settlement.
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."