An organiser with Britain’s biggest trade union has been jailed for her part in the Dover clashes in January.
Mum-of-two Michelle Smith travelled from her home in Liverpool to join a left-wing march against racism in the town.
But the £37,000-a-year official with Unite The Union was caught on camera throwing rocks at far-right demonstrators.
Judge Adele Williams watched a 14-minute composite video showing the 41-year-old, sporting a Russian-style hat, joining in the battle as police tried to keep the two factions apart.
Smith was seen on at least four occasions hurling missiles over the heads of officers as people around her shouted obscenities.
She is finally seen fighting with a woman near the BP garage and later handed herself in to police.
Now she has been jailed for a year after pleading guilty to violent disorder in the town.
Prosecutor Andrew Espley said Smith became involved in what had started as an anti-immigration demonstration and she was part of a counter demonstration.
DC Tom Banks told Canterbury Crown Court police had 500 hours of footage from the clashes on January 30.
He said Smith was seen to throw objects on four occasions before she ended up fighting with another woman.
A senior probation officer, Linda Jaycock, who interviewed Smith prior to sentence, said she had come to Dover as part of an anti-racist demonstration and claimed she came under attack from the rival group.
Ms Jaycock added Smith told how she had been involved in many demonstrations in the past which had always been peaceful.
“She said she admits throwing missiles and knows she shouldn’t have done, but blamed it on a loss of control. She was later threatened by a skinhead.
“She works full-time as an official for the union and has done for 12 years,” she added.
Benjamin Narain, defending, said Smith was genuinely sorry, but denies throwing at police.
“This isn’t what she normally does. She did not go there with the intention of causing violence. This offending is an aberration, a complete lapse of judgement and out of character.”
The barrister said Smith normally is involved in community campaigning, attending council meetings, demonstrations against racists, public meetings, and organising a food bank.
“As a result she is on a Watch List for a whole herd of unpleasant organisations, including Red Watch, North-West Infidels, Scouse Nationalists and others who have published her photograph.”
He claimed she has been stalked and physically attacked at her place of work in Liverpool.
Jailing her, the judge said she had read testimonies of Smith’s responsible work, which contrasted with her acting highly irresponsible when the violence began.
“The responsible decision would have been to leave the area at once,” said the judge.
“It is a tragedy you involved yourself in these events.”
After sentencing, PC Pete Frampton said: "The level of violence displayed on that day was truly shocking and Michelle Smith played a key role, often seen at the front of her group of protestors as they fought with others.
"The laws of this country allow peaceful protest but the actions of Smith and others arrested since then were most certainly not peaceful, nor what anyone would expect to witness in a civilised society.
"She is the 13 person to have been sentenced for her actions thus far, with some of those receiving prison sentences totalling almost 14 years.
"There are many more awaiting their day in court and I hope this sends a clear message that such violence will not be tolerated in Dover or anywhere else in Kent."