Sidney Rittenberg, an American soldier-linguist who stayed in China for 35 years after World War II as an adviser and political prisoner of the Communist Revolution, and later made millions as a counselor of Western capitalists exploiting booming Chinese markets, died on Saturday August 22 2019 in Scottsdale, Ariz. He was 98. Mr. Rittenberg was a dedicated aide to Chairman Mao Zedong and Premier Zhou Enlai as a party propagandist known across China by his Mandarin name, Li Dunbai. But he ran afoul of Mao’s suspicions, offended Mao’s wife and spent 16 years in prison. In the United States after his release, he used his extensive knowledge and contacts in China to build his own capitalist empire, advising corporate leaders, including Bill Gates of Microsoft and the computer magnate Michael S. Dell. He founded Rittenberg & Associates, a consulting firm for American companies doing business in China. He joined the Chinese studies faculty at Pacific Lutheran University in Tacoma, Wash., and wrote about China’s markets for the Strategic News Service, a weekly business digest. Mr. Gates and Mr. Dell were readers. Over the years, his services were engaged by hundreds of venture capitalists and American companies, including Microsoft, Intel, Prudential Insurance, Polaroid and Levi Strauss. He made a half-dozen business trips to China annually, and kept an apartment in Beijing. He was well paid and lived with his third wife, Wang Yulin, and their three daughters and son in a Beijing suite luxurious even by Western standards, filled with priceless Ming dynasty antiques. (He had previously been married to an American who divorced him when he left for China, and to Wei Lin, a Chinese state radio announcer who, as a gesture of solidarity with the party, divorced him after he was accused of espionage.) The Rittenbergs later bought a home on Fox Island, Wash., overlooking Puget Sound, a condo in Bellevue, Wash., and a home in Scottsdale, Ariz. Mike Wallace of CBS and the Rev. Billy Graham were among their friends. He is survived by his wife and children, Xiaoqin (Jenny), Xiaodong (Toni), Xiaoxiang (Sunny) and Xiaoming (Sidney Jr.), and four grandchildren.