Adam B. Ulam, Gurney professor of history and political science emeritus and a world-renowned expert on the history of the Soviet Union, died of lung cancer Tuesday at Youville Hospital in Cambridge. He was 77.

Ulam served as director of Harvard's Russian Research Center from 1973 to 1976 and from 1980 to 1992. A prolific writer, his works included The Bolsheviks and Stalin: The Man and His Era, considered by academics to be among the most important profiles of Lenin and Stalin, respectively.

A member of a wealthy Jewish family, Ulam was born in Lvov, Poland in 1922 and lived there until age 16.

In August of 1939, Ulam's father insisted that he and his brother flee Poland for fear of Hitler. Days later, Germany invaded Poland.

According to Ulam's ex-wife, Mary Burgwin Ulam, his was the last boat to leave Poland for America before the attack.

In the U.S., Ulam's brother Stanislaw held a junior fellowship at Harvard and used his salary to support them.

"Stan supported Adam," Burgwin Ulam said. "It was hard because there was little money."

Stanislaw Ulam, a mathematician who helped build the hydrogen bomb, initially supported Ulam at Brown University.