Holt was sworn in as prime minister on 26 January 1966, following the retirement of Robert Menzies six days earlier. He won the leadership election unopposed, with William McMahon elected as his deputy. His swearing in was delayed by the death of Defence Minister Shane Paltridge; he and Menzies both served as pallbearers at Paltridge's state funeral on 25 January. Holt was the first Australian prime minister born in the 20th century and the first born after federation. He was almost fourteen years younger than his predecessor, but, at the age of 57, was still the fourth-oldest man to assume the office.