John Lawrence Sullivan, 83, a secretary of the Navy in the Truman administration who resigned in 1949 in a dispute over defense policies, died Aug. 8 in a hospital in Exeter, N.H. He had a heart ailment.

Mr. Sullivan, who maintained homes here and in Manchester, N.H., was a lawyer by profession. He retired last year from the Washington law firm of Sullivan, Bernard, Shea & Kenney, which he had helped to found in the mid-1940s.

A native of Manchester and a World War I veteran of the Navy, Mr. Sullivan moved to Washington in 1939 as an assistant to the commissioner of the Internal Revenue Service. He was assistant secretary of the Treasury from 1940 to November 1944. He practiced law until July 1945, when he became assistant secretary of the Navy. He was named under secretary in 1946 and secretary the following year.

He was the first Navy secretary not to serve in the president's cabinet. The National Security Act of 1947 established the Defense Department with secretaries of the Navy, Army and Air Force reporting to the secretary of Defense. James Forrestal, the secretary of the Navy when the act went into effect, was named the first secretary of Defense. Mr. Sullivan succeeded him as Navy secretary.

In the years immediately following World War II, the Air Force was regarded as the premier strategic service. Its ability to deliver nuclear weapons was thought to have reduced the danger of conventional war and so it got the major share of defense appropriations. The Army was equipped for its traditional role of fighting land wars. Since the United States already was the major sea power in the world, the Navy received a smaller share of the arms budget.

As Navy secretary, Mr. Sullivan fought for a modern fleet, including the construction of a "super carrier," the 65,000-ton United States. Unlike existing carriers, it was designed to launch B-29s, the heavy "Superfortress" bombers. This would have given the Navy a way to deliver nuclear weapons to targets far inland.

In 1949, Defense secretary Louis Johnson canceled construction of the United States, saying the $189 million price tag was too great. Mr. Sullivan disagreed. He turned in a formal letter of resignation to President Truman and blasted Johnson in another letter of resignation. He accused the Defense secretary of denying the Navy a weapon that twice had been approved by the president and Congress. He also accused Johnson of planning to abolish the Marine Corps.

Mr. Sullivan was a 1921 graduate of Dartmouth College and a 1924 graduate of the Harvard law school. A Democrat, he served as county solicitor in Manchester and was twice defeated for governor of New Hampshire by Styles Bridges.

He was a member of the American, New Hampshire, and D.C. bar associations. He was a president of the Burning Tree Country Club and a member of the Chevy Chase Club.

Survivors include his wife, Priscilla M., of Manchester and Washington; a son, Charles M., of Cambridge, Mass.; two daughters, Patricia Meyers and Deborah DuSault, both of Washington, and five grandchildren.