A security guard stopped a date rape attack after seeing it on CCTV and shouting over a Tannoy: "Get off her, she's drunk."
Turkey Al-Turkey, 26, got the woman unconscious before dragging her off a park bench to rape her on a lawn.
Security guard Richard Arnold noticed she was "completely motionless" and went on the Tannoy to warn Al-Turkey he had called 999.
Police believe Al-Turkey used a date rape drug on the university graduate, 24, who has no memory of the attack in Swansea, South Wales.
Al-Turkey, originally from Iraq, was jailed for eight years and eight months after admitting rape on July 18 this year.
The pair bought vodka, although the woman was a non-drinker, and walked to the seafront promenade, Swansea Crown Court heard.
Prosecutor Carina Hughes said: "Security guard Richard Arnold could see them on CCTV and noticed the woman's head was floppy and she was unable to stand.
"The man picked her up from the bench took her 20 steps onto the grass where he raped her.
"Mr Arnold shouted over the Tannoy system: 'Get off her, she's drunk, I've phoned the police.'
"Upon hearing that, the defendant immediately got up and looked around before pulling up his and her trousers and going back to the bench."
The victim only became aware that she had been raped after being interviewed by police. She refused to view the CCTV for fear of getting flashbacks.
Miss Hughes told the court: "Police and the prosecution believe a date rape drug was used.
"Her level of unconsciousness was over and above what would be expected with alcohol."
In a victim impact statement, the woman said she had no recollection of what happened to her.
She told Swansea Crown Court: "The joy of life has left me - he violated my body and soul."
Judge Paul Thomas told Al-Turkey: "You took cruel advantage of the situation for your own sexual needs and she was wholly unaware what happened to her until the police told her."
Al-Turkey, of Brynhyfryd, Swansea, was ordered to register as a sex offender for life and will be deported when freed from jail.