Carl S. Wallace, 63, an assistant secretary of the Army and a special assistant to the secretary and the deputy secretary of Defense in the Nixon administration, died of cancer Sept. 23 at his home in Alexandria.

Mr. Wallace began his Washington career in 1965 as administrative assistant to then-Rep. Melvin R. Laird (R-Wis.), who became secretary of Defense in the Nixon administration. He accompanied Laird to the Defense Department in 1969 as a special assistant to the secretary and to David Packard, the deputy secretary.

He held these positions until 1973, when he was appointed assistant secretary of the Army for manpower and Reserve affairs. He resigned in 1974. Since then, he had headed the Washington office of Purolator Inc., as a corporate vice president.

Mr. Wallace was born in Ontario, Wis. He graduated from the University of Wisconsin, served in the Army in Europe during World War II, and then joined the Wisconsin State Employment Service. From 1954 to 1965, he was manager of the Chamber of Commerce in Stevens Point, Wis.

For his government service, Mr. Wallace received the Distinguished Public Service Medal of the Defense Department and the Distinguished Civilian Service Medal from the Army.

He was a member of the Burning Tree Club, the Business Government Relations Council and the Laird Youth Leadership Foundation.

Survivors include his wife, the former Marian Jones, whom he married in 1941, of Alexandria; a son, Carl S. Jr., of Westchester, Pa.; a daughter, Mary Ann Green of Friendly, Md., and two grandchildren.