Retired Army Brig. Gen. Lawrence P. Jacobs, 65, who helped to establish the area grid communications systems concept, died Thursday of pneumonia at Walter Reed Hospital.

In a letter to Gen. Jacobs, after his retirement in 1966, Gen. Harold K. Johnson, then chief of staff, called the communications system "one of the greatest advancements in military communications techniques since World War II."

Before the "grid" system came into general use, communications among fighting forces were based on hierarchy, with lieutenants linked to captains, who in turn were linked with their superiors for communication.

The "grid" system allows troops to move within the battle area and "plug" into the system as they progress. The system is linked to everyone in the fighting force, regardless of rank.

Gen. Jacobs began his career with the Army as a platoon leader in the 56th Signal Battalion. He then became an aide in the office of the chief signal officer during the early stages of World War II.

Gen. Jacobs continued his work in communications when he became chief of the plans branch office, European Command, and commanding officer of the 7772d Signal Battalion.

It was as chief of the engineering and supply division of the Army Signal Board and later as deputy president of the board that Gen. Jacob's helped to create and put into use the "grid" communications syste.

Later, as chief of the plans programs and operations division, and therefore chief planner for the Signal Corps, he helped to developed a "strategic communications support system" for use by military forces in emergency situations.

He then became the chief signal officer for the Army in the Pacific where he "supervised the expansion and improvement of Army-operated communications systems throughout the Pacific area and Southeast Asia," according to Gen. Johnson's letter.

Gen. Jacobs' last assignment was as deputy chief of communications electronics for the Army. He retired in April, 1966.

The general, who was born in Houston, Tex., attended schools in Columbus, Ga., and graduated from Georgia Institute of Technoloty in Atlanta with a B.S. in electrical engineering.

He was then commissioned as a 2d lieutenant with the Army Signal Corps.

He is survived by his wife, Cogee, of the home in Arlington; a daughter, Barbara A. Hobbs, of Clark County, Va., and two grandchildren, Virginia E. Wells and Lawrence R. Wells.