Forged by the development of radar during World War II, radio astronomy revolutionized astronomy during the decade after the war: a new universe centered not on stars and planets, but on the gas between the stars, on explosive sources of unprecedented luminosity, and on hundreds of mysterious discrete sources with few optical identifications. Using "radio telescopes" that looked nothing like traditional (optical) telescopes, radio astronomers were also a very different breed from traditional (optical) astronomers. This talk will trace the history of radio astronomy from 1945 through about 1953, focusing on the development of interferometric techniques by Ryle's group at Cambridge, Pawsey, Mills and Bolton in Sydney, and Hanbury Brown at Jodrell Bank.