Three retained fire stations which protesters waged a long-running campaign to save are to close following a review of the service in West Sussex.
West Sussex Fire and Rescue Service unveiled the decision on Tuesday and said the changes would bring operations into the 21st Century.
The stations at Bosham, Findon and Keymer will close.
The Fire Brigades Union (FBU) and the Retained Firefighters' Union (RFU) said campaigners had not been listened to.
A statement from the council and fire service said the stations to be closed were in low-risk areas and had a low number of emergency calls.
Two other retained fire stations - Burgess Hill and Littlehampton - would be upgraded and crewed by whole-time firefighters at peak times.
Three fire engines were being redeployed under the terms of the plan. The fire service said the second fire engines at stations in East Preston, Lancing and Horley, could be used more effectively elsewhere.
Improvements included better training and safety for firefighters, increased community activities to prevent emergencies occurring in the first place, and efficiency savings of £1.2m, it was claimed.
But Tristan Ashby, from the RFU, said: "With six fewer fire engines and three fewer fire stations and dozens fewer retained firefighters, the people of West Sussex are not going to be safer."
He said thousands of people had signed petitions against the proposals in Findon, Lancing and Keymer.
Mr Ashby claimed response standards would only get worse, more money would have to be spent on upgrading stations, and the fire engines that were being redeployed were actually being removed.
Mick Cambers, FBU West Sussex chairman, said there had not been enough scrutiny of the proposals by the county council.
He said night cover was being degraded, response standards were getting worse, and the improvement plan would leave the county with a "stretched service".
"Regarding whether this will improve the service, there is no proof of that. We won't have proof until these changes are made," he added.
He said the FBU understood that savings needed to be made but it opposed a "quick rush to the front-line end of the service".
But West Sussex Councillor Peter Evans, cabinet spokesman for public protection, who approved the fire service's improvement plan, said the brigade would be more effective, public safety would be improved, and resources would be used more effectively.
"Higher risk areas will be targeted, so improving safety for vulnerable people, and there will be overall improvements to response times across the county," he said.