Col. (USMC ret.) and Mrs. Leslie Arthur Gilson of this city announce the engagement of their daughter, Margaret Tillman to Henry Alexander Thompson, son of Dr. and Mrs. John Alexander Thompson of Princeton, N.J. A December wedding is planned.

Miss Gilson attended Holton-Arms School and graduated from the Madeira School. Mr. Thompson attended the American School in Alexandria, Egypt, and graduated from Stonybrook School, Long Island, N.Y. The betrothed are graduates of Georgetown University School of Foreign Service, where Miss Gilson belonged to Phi Alpha Theta, honorary historical society. She was an intern at the White House and is now with the Department of State. Her fiance is governmental and labor relations officer with HBH Company in Jubail, Saudi Arabia.

The future bride's father is with the Department of Defense. She is the great-granddaughter of the late U.S. Circuit Court Judge and Mrs. Ormond Woodward Buchanan of Winnsboro, S.C. and of the late Congressman and Mrs. George D. Tillman of Edgefield, S.C. She is a direct descendant of Roger Tilghman, who founded Fort Tillman in 1689 on a land grant in Dinwiddie County, Va.

Mr. Thompson's parents are ordained Presbyterian ministers who were engaged in biblical and archaeological studies for many years in Egypt. His father is a consultant with the American Bible Society in New York, and his mother is Protestant Chaplain of Trenton State College. His maternal grandfather, the late A. Henry Birkel, was an artist and a missionary to China. Biblical scholars and archaeologists were his paternal grandfather, Forest Scott Thompson, and his great-grandfather, the late John Romich Alexander, founder of Assuit College in Assuit, Egypt.