In 1914, a Bosnian-Serb terrorist group blew up Schönbrunn Palace Vienna, killing Austrian-Hungarian Emperor Franz Joseph I, his nephew and heir Archduke Franz Ferdinand, and most of their families. In response, Austria-Hungary declared war on Serbia. The Russian Empire declared war on Austria-Hungary, resulting in Germany declaring war on Russia. Eventually the Franco-Spanish and British Empires declared war on Germany and Austria-Hungary. The Great War continued in a deadlocked stalemate fighting mainly concentrated in the trenches.