Christopher Hill, 91, a brilliant and controversial British Marxist historian who was a leading interpreter of England's Civil War era from 1640 to 1660, died Feb. 24 at his home in Oxfordshire, England. He had Alzheimer's disease.

Mr. Hill, who spent nearly his entire career at Britain's Oxford University, became famous for his Marxist interpretations of the war that pitted Roundhead against Cavalier as well as Puritans and other nonconformists against the Church of England.

He maintained, unlike most historians, that the civil war was not a simple evolution of English history and government but was as true a revolution as those in 18th-century France and 20th-century Russia. His work involved examinations of 17th-century English literature, economics, politics and religion, as well as social history in general.

He proposed that the revolution featured a class conflict involving rich landowners, urban bourgeoisie and lower orders of peasants and artisans.

Critics and fellow historians questioned his Marxist bias. Others regarded him as an unrepentant Roundhead who had an all too obvious affection for such unusual radical nonconformist sects as Levellers, Ranters and Muggletonians.

But the British historian E.P. Thompson called Mr. Hill "the dean and paragon of English historians," while the New York Review of Books wrote that "the age of the Puritan Revolution must now be regarded as 'Hill's half-century.' "

The prestigious British Times Literary Supplement hailed both Mr. Hill's literary output (more than 25 books and hundreds of technical articles) and his knowledge and skill with source material: "Taken separately his productivity and his erudition are monumental, taken together they are incredible."

He explored the Civil War and its era in such books as "The Economic Problems of the Church from Whitgift to the Long Parliament" (1956), "Puritanism and Revolution" (1958), "The Century of Revolution" (1961), "Intellectual Origins of the English Revolution" (1965), "Reformation to Industrial Revolution" (1967), "The World Turned Upside Down" (1972) and "Change and Continuity in Seventeenth Century England" (1974).

Mr. Hill also compiled collections of his magazine essays and journal articles and published books on such smaller topics as "The Muggletonians" (1983). He also wrote biographies of such figures as John Milton and Oliver Cromwell.

John Edward Christopher Hill was born in York, England. His father was a lawyer, and both parents were Methodists. Mr. Hill maintained that his parents' dissenting religion contributed to his own radical outlook on social life and politics.

He received a first in history from Oxford's Balliol College in 1934 and a master's degree in 1938. He received numerous academic honors, including the university's top intellectual honors, a fellowship at All Souls College. He was perhaps equally well known at Balliol for leading it to a university rugby championship.

He taught history at University College, Cardiff, Wales, from 1936 to 1938, then returned to Balliol as a fellow and modern history tutor. He held those positions until his election as master of Balliol College, a post he held from 1965 until retiring in 1978.

Mr. Hill spent 1935 in the Soviet Union, where he studied Russian language and history. He became a member of the British Communist Party in pre-war Balliol.

During World War II, he was commissioned in the British Army's Oxford and Buckinghamshire Light Infantry. Later in the war, he served in the Army Intelligence Corps, attaining the rank of major, and the British Foreign Office.

In 1947, a fellow Oxford historian, the brilliant and opinionated A.L. Rowse, asked him to contribute a volume on Lenin to the Teach Yourself History series he was editing. In his book "Historians I Have Known," Rowse recalled that upon receiving the manuscript, "I was taken aback -- a work of stone-walling Stalinist orthodoxy, not a whit human."

"Lenin and the Russian Revolution" became the best-selling volume in the series.

As a tutor, Mr. Hill gained a reputation as a brilliant and surprisingly nondogmatic teacher who cared deeply about his students. However, one student recalled his "forbiddingly high standards."

Mr. Hill, who resigned from the Communist Party following the Soviet suppression of the 1956 Hungarian uprising, was a fellow of the British Academy.

His first marriage, to Inez Waugh, ended in divorce. His second wife, the Oxford feminist historian Bridget Sutton, whom he married in1956, died last year.

Survivors include three children.