Shortwave broadcasts from abroad assumed enormous importance during the war years. In September 1939, the BBC began broadcasting in Czech from London, headquarters of the Czechoslovak government-in-exile. Shortwave broadcasts from Moscow - the centre of exile Communist activity - began in Czech in 1941, and a year later the Czech service of Voice of America took to the airwaves. Listening to foreign radio in the occupied Czech Lands was a crime punishable by death, and people were forced to have shortwave circuits removed from their radios so they would be unable to listen to foreign programmes. But people continued to listen to shortwave - some listeners even fitted illegal circuit replacements - nicknamed "Churchills" - to their doctored radios so they could continue to receive shortwave. Foreign radio served as a crucial source of information and morale for the people living in the occupied lands.
Radio, the most powerful of media, was an active participant in the Prague Uprising, which marked an end to the Nazi occupation of the Czech Lands. The uprising, organised by the Czech resistance, began on May 5th 1945 with a call to arms, broadcast on the radio. The uprising soon became to a large extent a battle for control of the radio station itself. The shortwave transmitter joined the struggle, broadcasting a plea for help to the Allied armies on May 6th. Dozens laid down their lives to protect the building, and the broadcasts continued uninterrupted.