Bulgaria–United States relations to work. Bulgaria became a member of the Warsaw Pact on May 14, 1955. Though no Soviet troops were stationed on Bulgarian soil, in 1968, Zhivkov sent a Bulgarian division to join Polish, Hungarian and Soviet troops to crush a popular uprising in Prague. In 1978, the Bulgarian secret police were implicated in the assassination in London of Georgi Markov, a Bulgarian dissident who was a correspondent for the BBC World Service, Deutsche Welle radio and the U.S. sponsored Radio Free Europe. Markov was assassinated with a poisoned umbrella on September 7, Zhivkov's birthday. The rise of democratic movements across
Waterloo Helmet Waterloo Helmet The Waterloo Helmet (also known as the Waterloo Bridge Helmet) is a pre-Roman Celtic bronze ceremonial horned helmet with repoussé decoration in the La Tène style, dating to circa 150–50 BC, that was found in 1868 in the River Thames by Waterloo Bridge in London, England. It is now on display at the British Museum in London. The helmet was dredged from the bed of the River Thames close to Waterloo Bridge in 1868, and in March of the same year it was given on loan to the British Museum by Thames Conservancy. In 1988 its successor body,