Roy Kirklin Davenport, 78, a career civil servant who rose to be deputy assistant secretary of defense for manpower planning and research in 1966 and who was the highest-ranking black in the defense establishment up to that time, died June 2 at the Fernwood House nursing home in Bethesda. He had Alzheimer's disease and pneumonia.

Mr. Davenport joined the federal government in 1941 as a $2,000-a-year social science analyst in the Department of Agriculture. The following year, he took a job in the Office of the Adjutant General of the Army in the old War Department. The work of the adjutant general is personnel and this became Mr. Davenport's career. By the end of the war he was directing a staff of 500.

He remained in his field when the War Department was absorbed into the new Defense Department in 1947, and in 1961 he was named deputy under secretary of the Army for personnel. He held that post until 1966, when he was named deputy assistant secretary of defense for manpower, a job that carried rank equivalent to that of a full general. He retired at the end of 1966 for reasons of health.

Over the years Mr. Davenport's work ranged from directing literacy programs for new recruits to coordinating personnel management matters among various government agencies and private industry. His duties took him from South Korea and Japan to France and West Germany.

But he said he thought his greatest contribution came in the second Truman administration, when he played a part in carrying out the president's orders to integrate the armed forces. Among other things, he testified before Judge Charles Fahy, the chairman of a study committee established by President Harry Truman. The impact of Mr. Davenport's appearance was attributed to the fact that he was virtually the only high defense official, black or white, with a complete knowledge of how blacks were treated in the military.

Mr. Davenport twice received the Exceptional Civilian Service Award, the highest honor the Army confers on civilians. His other honors included the Meritorious Service Award, a merit citation from the National Civil Service League and outstanding performance awards in 1954 and 1960.

A native of Oakland, Calif., Mr. Davenport grew up there and in Springfield, Mass. He graduated from Fisk University in Nashville, and earned a master's degree in psychology at Columbia University in New York. He taught at Langston University in Oklahoma and at South Carolina State College in Orangeburg, S.C., until moving to Washington.

In retirement, Mr. Davenport lived in Washington and then in Solomons Island, Md. In 1978, after the death of his wife, the former Ruby Bates, he moved to Columbia, Md., and shortly after to Greenbelt. He had been in the Fernwood nursing home since 1984.

Survivors include two children, Helen Kay Bradby of Washington and Roy Kirklin Davenport Jr. of Exton, Pa.; one sister, Floyd Liburd of Springfield Gardens, N.Y., and six grandchildren.

Shortly before he left government -- he declined to have the occasion marked by a reception -- Mr. Davenport was asked by a reporter for the North American Newspaper Alliance if he thought race had been a factor in his career.

"I was rarely concerned about race," he replied, "but I was concerned about people and utilizing their fullest potential."

And he was asked if he had any thoughts for young blacks.

They have to "move beyond ordinary occupations," he said. "They must be willing to risk entering new fields and taking their chances competitively. You can't meet job competition solely by marching and protesting. You must keep your nose in your books and prepare yourself."