About 3,500 people took part in a protest in Brighton and Hove today against changes to public sector pensions.
Others picketed schools and other public buildings and went on strike.
A march and rally passed off peacefully although later four people were arrested in Brighton for public nuisance and aggravated trespass offences.
About 50 state sector schools, colleges and nurseries throughout Brighton, Hove and Portslade were forced to close – or just over two thirds of the total.
Teachers and lecturers were prominent among the public sector workers taking action.
They are angry that pension changes mean that they will have to pay more, work longer and receive less when they retire.
Some pupils and students joined the protest as did Simon Burgess, the former Labour leader of Brighton and Hove City Council.
He said: “I’m not a teacher but I value hugely what they and other public sector workers do.
“They deserve our support. If this government gets away with this it will be our police, NHS and firefighters’ pensions next.
“Public sector workers did not cause the banking crisis. They should not be the ones left to pay for it in their retirement.”
Mr Burgess took part in the march from The Level to Hove Town Hall with colleagues from Hamilton Lodge Deaf School.
Brighton Pavilion Green MP Caroline Lucas said: “Public sector pensions are affordable.
“This is really about piling the UK’s debt burden on to the people who did the least to create it.
“I believe that fair pensions are worth fighting for, so I will be joining the picket lines in solidarity with my constituents.
“I regret the disruption caused by industrial action and think it must only be used in special circumstances and would urge trade unions to work hard to ensure support from the wider public.
“Yet when teachers are being expected to pay 50 per cent more in pension contributions, work longer and get less pension when they retire – and when negotiations are failing – targeted and considered action is clearly necessary.”
Superintendent Steve Whitton from Sussex Police said: “We were glad that the earlier demonstration passed off peacefully and without protracted disruption, bearing in mind the extraordinary number of persons marching.
“I would also like to thank the organisers for their co-operation while the policing operation was being planned.”
Four people – three men and a woman – were arrested at about 3.30pm.
Superintendent Whitton said: “Some time after the large peaceful demonstration had taken place, a group of approximately 25 were responsible for an assault against staff in Churchill Square and disruption within Boots and Barclays Bank which prevented and obstructed staff and customers.
“This behaviour went beyond peaceful demonstrating and significantly infringed upon the rights of other members of the community who would expect us to act.
“We consider that this action was completely unrelated to the earlier demonstration and conducted by individuals who have little regard for the rights of others in the city.
Nationally up to 750,000 teachers, civil servants and other public sector workers went on strike over the pension changes planned by the Conservative and Liberal Democrat coalition government.
Among the organisations affected by the strikes were airports, the coastguard, courts, driving test centres, job centres and prisons.