L. Mercer Smith, 73, retired vice president and general manager of the C&P Telephone Co. of Maryland, died July 20 in Castine, Maine, after suffering a stroke while vacationing there.

He retired in 1971 after 11 years as the Maryland telephone company's chief operating officer.

Mr. Smith was born in Washington. A graduate of Yale University, he attended George Washington University Law School.

He joined C&P in Washington as a clerk in the commercial department in 1929 and rose to become division commercial manager here.

In 1949, Mr. Smith became general commercial manager of the Maryland company. Ten years later he transferred to C&P's Group Headquarters in Washington as vice president for marketing. He returned to the Maryland company offices in Baltimore a year later.

Mr. Smith was a director of C , the First National Bank of Maryland, the Provident Savings Bank, Maryland Casualty Co., American General Insurance Co. and Sinai Hospital of Baltimore.

He was on the boards of the University of Maryland, Goucher College and the Association of Independent Colleges of Maryland, and was active in many civic groups in the Baltimore area.

He is survived by his wife, Dorothy, of the home in Baltimore; a son, H. Duff, and a daughter, Elizabeth S. Esher, both of Baltimore, and five grandchildren. CAPTION: Picture, L. MERCER SMITH