Gdansk, Poland — Lech Walesa, who led the now-banned independent trade union Solidarity, walked in a church procession carrying a charred wooden cross. About 2,000 people, including many former union members, took part in the traditional Palm Sunday mass near Gdansk's giant Lenin Shipyard, where Solidarity was born in August 1980. The procession was confined to the church and its precincts. A day earlier, a Polish newspaper accused Mr. Walesa of exploiting what it called sensational reports of attempts on his life. The article, one of the sharpest attacks in recent months, referred to Italian investigations into an alleged plot to kill him in Rome two years ago.