A Good Samaritan who tried to prevent a young woman from being abused was then attacked by up to six youths.
Swindon Police are appealing for witnesses to the assault, which happened just after 10.30pm on Tuesday, 1 September at the subway between the town centre and the bus station.
A spokesman said the victim was attacked after attempting to intervene when he saw a woman being abused nearby.
He was repeatedly kicked in the face and head while on the ground, leaving him with multiple bruises. He was taken to hospital as a precaution.
The police want to speak to anybody who saw the attack, and especially another Good Samaritan who helped the assault victim.
Anybody with information is asked to call 101 and quote crime reference number 54200087807.