Claudius had some kind of disability, in speech and walking, and his family kept him from public office until he was 38. Claudius' infirmity may have saved him from the purges of Tiberius' and Caligula's reigns; enemies did not see him as a serious threat. He was declared emperor at the insistence of the Praetorian Guard after Caligula's assassination. He was then the last adult male of his family.