When last Sunday Pope Francis took the brave step of acknowledging the Armenian tragedy as the ‘first genocide of the 20th century’, he knew he was entering a minefield. On 24 April Armenians will commemorate the 100th anniversary of their genocide. There can be no single date for a genocide but that was the day the entire leadership of the Armenian people was arrested by the Ottoman government in Constantinople, now Istanbul, whose successors are the modern Turkish state.