Rishi Sunak issued a plea for “unity” amid tensions over the march - set to go ahead on the day the UK marks the anniversary of the end of the First World War.
Concerns about the risk of counter-protests, particularly around the Cenotaph, were well founded, with scuffles between far-right groups and police breaking out nearby.
Scotland Yard will deploy nearly 2,000 officers across central London in a major policing operation over the weekend.
On the eve of the mass protest, the prime minister urged those taking part to do so “respectfully and peacefully” and to respect Armistice Day commemorations.
“This act of remembrance is fundamental to who we are as a country and I want to reassure those wishing to pay their respects, attend services and travel that they can and should do so,” Mr Sunak said in a statement.