Protesters are voicing their anger over the brutal Zoom sacking of 800 P&O Ferries employees.
The 800 workers were sacked immediately, with no notice, and are set to be replaced by agency workers, leading to services halting at 11am on Thursday.
Security guards wearing balaclavas boarded ships with handcuffs to remove fired crew, it was alleged.
Sacked workers from P&O began to gather outside the National Union of Rail Maritime and Transport Workers building in Dover from 11am today.
Many RMT flags with "Save Our Seafarers" were planted in the grass outside.
Other members waved banners at passing drivers who honked their horns in solidarity.
One former employee, who had been advised by the union not to give his name to protect his redundancy package, called on locals to join their march.
The staff member of 22 years, aged in his 50s, said: "We need as many people as possible to help us make a stand. I want the whole town out.
"P&O was an institution in Dover. If you didn't work there, you knew someone who did.
"Their reputation is ruined, not just here, but nationwide."
It comes as P&O have today released a statement, acknowledging that the redundancies came "without warning or prior consultation" and has caused "distress for them and their families".
The "difficult" decision was taken as a last resort after full consideration of other options, it said and in good faith that in reaching an agreement on a way forward would be "impossible".
“We have offered enhanced severance terms to those affected to properly and promptly compensate them for the lack of warning and consultation," it said.
All affected crew who were working yesterday were notified face to face and in-person on board their vessels, the statement said, while crew who were off were contacted by email, phone call, text, or over a virtual meeting. Around 261 of the 800 affected staff were on those calls, the statement said.
The protest action comes as Downing Street today threatened P&O Ferries with "ramifications" over the sackings. Boris Johnson is facing furious demands to act as the hundreds of workers are left in the lurch.
The mass sacking has led to widespread confusion at ports with passengers taken off ferries and told to await information amidst rumours they would need to use other services.
Around 200 people made the 20 minute walk to the Port of Dover before standing on the roundabout blockading the entrance while union leaders made speeches.
After around 15 minutes, police urged protesters to clear one lane so traffic could pass, which demonstrators complied with while listening.
The group dispersed at 1.20pm and began walking back to the Union headquarters.
Ms Elphicke was at the front of the march holding a banner alongside former Labour shadow chancellor John McDonnell.
He said: "Brothers and sisters I'm here in 100 per cent absolute solidarity with your struggle.
"We've just had the meeting with Keir Starmer and he should now demand a meeting with the legal officers of this government to discuss what laws can be used to ensure the full reinstatement of all workers.
"And if there is a gap in the law, on Monday, to bring forward emergency legislation to ensure those jobs are secure. If they cannot find the legislation in time, seize the ships on Tuesday.
"Remember P&O like many other ship owners have had support throughout the Covid crisis. They've had grants made available to them.
P&O Ferries released a statement on social media saying: "Regretfully, P&O Ferries services are unable to run for the next few hours.
"Our Port Teams will guide you and travel will be arranged via an alternative operator. We apologise for the inconvenience this will have on your journey plans."
Transport Minister Robert Courts told the Commons today: “This is an emerging story which is causing great concern.”
Workers were hauled off ships by men in balaclavas as the company made 800 staff redundant , an MP has claimed.
Staff on board P&O ferries were ordered to leave, some with just five minutes' notice.
But the crew of the P&O vessel Pride of Hull are refusing to leave out of protest.
Labour MP Diana Johnson told the Commons today: "I understand from the RMT union [the National Union of Rail, Maritime and Transport Workers] that these agency staff, mainly from overseas, are in buses on the quayside with a security firm... wearing balaclavas and taking British crew off these ship.
She added: "This is shameful and it goes against all norms of fair and reasonable behaviour and it's clear that foreign ratings will be employed on terms that are less favourable than our current UK seafarers are.
"And this is about a race to the bottom in terms and conditions reminiscent of the worst Thatcherite policies."
General secretary Mick Lynch of the RMT union said: "We are receiving reports that security guards at Dover are seeking to board ships with handcuffs to remove crew so they can be replaced with cheaper labour.
"We are seeking urgent legal action and are again calling for the government to take action to stop what is fast turning into one of the most shameful acts in the history of British industrial relations.
"If this happens at P&O it can happen anywhere and we are calling for mass trade union and wider public mobilisation and protest against the company."
More than 200 protesters gathered outside the Port of Liverpool.
Metro mayor of Liverpool Steve Rotheram, Greater Manchester mayor Andy Burnham and Sefton Central MP Bill Esterson joined the demonstration.
Labour MP Mr Esterson said: "I think we've got amazing solidarity from trade unions across the north of England and local people.
"Like everyone, I'm outraged at the appalling abuse of ordinary people by DP World."
Protesters held flags and signs, including one which said: "Shame on you!! P&O stop the carve up."
Lorry drivers on their way to and from the port beeped their horns in support.
