London's Grosvenor Square witnessed violent scenes after police moved in to remove protesters from the steps of the American embassy on this day in 1968.

The event, although unprecedented in scale, had begun in orderly fashion with an estimated crowd of around 80,000 gathering in Trafalgar Square to protest against American action in Vietnam and the British government’s support for the United States.

There they heard speeches from the likes of Tariq Ali, leader of the UK’s Vietnam Solidarity Campaign, and British actress Vanessa Redgrave, who announced that they would be delivering a letter of protest to the US embassy.

 Vanessa Redgrave and Tariq Ali at the demonstration of March 17, 1968

The pair then led around 8,000 protesters to Grosvenor Square where they found the US embassy surrounded by hundreds of police, standing shoulder to shoulder in a vast cordon.

Redgrave's group was allowed through to deliver the letter, but the crowd was held back and then refused to back off.

Stones, earth, firecrackers and smoke bombs were thrown as mounted police officers were called in to disperse the crowd.

By the time order was restored some four hours later, an estimated 300 people had been arrested and over 50 protesters and 25 police officers had been hospitalised.

The violence perpetrated on the streets of London knew no precedent and shocked the watching world, and the damage inflicted on police/public relations on March 17, 1968 reverberates to this day.

Do you remember the events of March 17, 1968? Share your thoughts in the Comments section below.