The war between the Roman Empire and the northern German tribes continued, and in May 15 AD Thusnelda was captured by Germanicus, the nephew of Emperor Tiberius, who commanded the invasion of Germania. She was pregnant and staying with her father, who was a Roman client and bitterly opposed to Arminius, and it was her father who delivered her to Germanicus, after the latter saved him by driving off Arminius' forces, who had besieged him. Her husband much grieved over her loss and did not marry again.
Her only by child by Arminius, Thumelicus, was born in captivity on 26 May AD 17. In AD 18, Arminius' brother Flavus reported that Thusnelda was being treated well by the Romans. Nothing is known of her after this date. Her son was trained as a gladiator in Ravenna, and is believed to have died in the arena around 30 or 31 when he was about 14 years old.