One of the most prominent figures in the far-right Alternative for Germany party arrived in court Thursday for his trial on charges of using a Nazi slogan, months before a regional election in which he is running to become his state’s governor. Björn Höcke, 52, is the leader of the regional branch of Alternative for Germany, or AfD, in the eastern state of Thuringia and a powerful figure on the party’s hard right. While never formally a national leader of AfD, the former history teacher has been consistently influential as the 11-year-old party has steadily headed further right and ousted...