Medals gleamed in the sun as they gathered in Tower Gardens to remember the fallen.
Wreaths were laid at the foot of the town's war memorial after a minute's silence.
David Norman, chair of King's Lynn British Legion, said: 'We are gethered here to remember the thousands who lost their lives in D-Day. They shall not grow old like those who are left.'
Some 25 veterans attended, although none of them were involved in the 1944 landings.
West Norfolk council leader Nick Daubney said: 'It's really important to remember, just imagine what those men and women faced.'
Mr Daubney said he had earlier welcomed visitors from Lynn's German twin town of Emmerich - a poignant reminder that the two nations were at war on this day.
Beneath the names of the 569 lost in the First World War on Lynn's memorial are inscribed those of 19 who died in the second.
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