A huge crowd gathered in Warsaw on Sunday in a display of antigovernment sentiment ahead of an election this month. Huge crowds marched through Poland’s capital, Warsaw, on Sunday, converging around a giant flag commemorating a 1944 uprising against Nazi Germany, as opponents of the governing party sought to rally voters for a critical general election that they see as the last chance to save the country’s hard-won democratic freedoms. The Warsaw city government, which is controlled by the opposition, put the crowd at a million people at its peak. But state-controlled television, which mostly ignored the event, instead broadcasting...