George Steinbrenner, who bought a declining Yankees team in 1973, promised to stay out of its daily affairs and then, in an often tumultuous reign, placed his formidable stamp on 7 World Series championship teams, 11 pennant winners and a sporting world powerhouse valued at perhaps $1.6 billion, died Tuesday morning. He was 80 and lived in Tampa, Fla. The Yankees announced the death without giving a cause. Mr. Steinbrenner’s death came eight months after the Yankees won their first World Series title since 2000, clinching their six-game victory over the Philadelphia Phillies at his new Yankee Stadium, and two days after the team’s longtime public-address announcer Bob Sheppard died at age 99. Mr. Steinbrenner had been in failing health for the past several years and rarely appeared in public. He attended the opening game at the new stadium in April 2009, sitting in his suite with his wife, Joan (pronounced Jo-ann). When he was introduced and received an ovation, his shoulders shook and he cried. MORE