Saburo Ienaga, 89, a Japanese historian who devoted his life to battling government censorship of Japan's wartime atrocities in school textbooks, died Dec. 1 at a hospital here. The cause of death was not reported.

He had been a professor at Tokyo University of Education, now University of Tsukuba. He began his court battles over textbooks in the mid-1960s and led the movement by teachers and their supporters against Japan's government textbook screening for nearly four decades.

In his most recent victory, the Supreme Court ruled in 1997 that the education ministry unconstitutionally blocked mention of Japanese wartime atrocities in Mr. Ienaga's 1983 text for high school students.

The removal involved passages on Japan's deadly experiments on Chinese prisoners even though the actions were established historical fact.

The ruling was the first time Japan's highest court had acknowledged a legal limit to the government's textbook screening. It also gave a further boost to teaching schoolchildren more about Japan's aggression in Asia in the first half of the 1900s.

Japan is one of the few countries that allows government textbook-screening.

Mr. Ienaga lost most of his court battles and sometimes required police protection from right-wing thugs who believed the historian had disgraced Japan and the emperor.

But many people believe his campaign helped to slowly relax censorship of war crimes from textbooks.

Some high school history textbooks now contain vague references to Asian women forced to serve as prostitutes for Japanese soldiers during World War II, and to slave laborers who were forcibly brought to Japan from Korea and China to dig tunnels and mines for the Imperial Army.