Police made four arrests as two rival protests were held in Cambridge on Saturday.
About 400 police officers were on duty as the English Defence League (EDL) protested against plans for a mosque and Unite Against Fascism (UAF) held a counter-demonstration.
Police said about 500 people took part in the UAF march through the city and about 30 attended the EDL protest.
They said their plan to manage both demonstrations had worked well.
Officers from Essex, Bedfordshire, Hertfordshire, Norfolk and Suffolk were drafted in to help their Cambridgeshire colleagues.
'Peaceful, although noisy'
A 56-year-old man from Cambridge was arrested on suspicion of being drunk and disorderly, a public order offence and assaulting a police officer and is in custody at Huntingdon Police Station.
Two more men, one 23 and from Cambridge, and a 24-year-old from Thetford, are also in custody at the same police station on suspicion of public order offences.
A 25-year-old man from Norwich was also arrested on suspicion of a public order offence and is in custody at Parkside Police Station, Cambridge.
UAF protestors marched through the city centre between midday and 14:00 GMT and the EDL held a protest at Christ's Pieces against plans for a mosque in Mill Road.
Both sides chanted at each other as they were kept apart by police.
Supt Vicky Skeels, of Cambridgeshire Police, said: "The two demonstrations have been peaceful, although noisy.
"The visible policing presence on the streets may have influenced the behaviour of some demonstrators and our open and positive style of policing has been well responded to by the community and the demonstrators."