Merkel invokes rise of Hitler to warn Germany against tyranny That must be a constant warning for us, Germans. Posters draped on landmarks, including the famous KaDeWe department store, contained biographies of the Jews, intellectuals and others who were targetted by the Nazis. At the former heaquarters of the Gestapo another exhibit showed photographs of the Reichstag burning and the first official poster issued by the Hitler government on April 1, 1933 declaring a boycott of Jewish businesses. Don't buy from Jews," it said. Hitler's appointment came just 10 years after his arrest for the botched beer-hall putsch in Munich and months after President Paul von Hindenburg contemptuously dismissed his bid for the leadership. The National Socialists won their largest share of the vote - 37 per cent - in the 1932 election. Diplomats were uncertain how long the new leader would last but George Messersmith, the US consul general in Berlin, was one of several to wrongly predict a period of political stability. "People are politically exhausted," he said. Within a year, the party's grip on power was absolute and a relentless war on its enemies had begun. At a special two-day session of the German Bundestag, leading politicans recalled recent "hate-crimes" against minorities and the stirrings of neo-Nazi parties. Norbert Lammert, the speaker, said it was necessary to bring Nazi horrors "to life everyday" so that the crimes are never repeated. He said: "The generation of witnesses is creating witnesses of witnesses." Separately German investigators have reportedly re-opened an investigation into one of the worst massacres of the Second World War when SS troops massacred 642 residents of the French village of Oradour-sur-Glane. A German prosecutor accompanied by police officers visited the abandoned village and spoke with the remaining two surviving eye-witnesses to the 1944 crime. More than 400 women and children were shot or burned alive in the attack. The case was reopened after a historian researching in the files of East Germany's Stasi secret police in 2010 discovered documents implicating six suspects, still alive and now aged between 85 and 86.