Robert Hugh Williams, 75, a retired brigadier general in the Marine Corps who won a Navy Cross, a Silver Star and a Purple Heart in the Pacific in World War II, died of cancer Feb. 15 at his farm, "Bryn Mawr," near Wales, Wis.

Gen. Williams was one of the first Marine officers to complete parachute training in World War II. He led a battalion of the 1st Marine Parachute Regiment in an amphibious assault on Gavutu in the Solomon Islands and there won the Navy Cross, the highest decoration for gallantry in the Naval service except for the Medal of Honor.

The citation said: "Fighting against very great odds, Lt. Col. Williams and his command daringly stormed strongly entrenched enemy forces and succeeded in securing a beachhead for further operations. Although he was wounded during the forward thrust, his outstanding aggressiveness and leadership were an inspiration to his entire battalion . . . ."

The Marine parachute regiment and raider battalions were disbanded later in the war and many of the men were assigned to the 28th Marines in the 5th Marine Division. They took part in the invasion of Iwo Jima and the 28th captured Mount Suribachi.

Gen. Williams, the executive officer of the 28th Marines, won the Silver Star during the assault on Suribachi while exposing himself to enemy fire and directing his men in the attack. "Lt. Col. Williams served as an inspiration to officers and men of his regiment and rendered invaluable assistance to his commanding officer during the Iwo Jima operation," the citation said.

Gen. Williams also took part in the campaigns for Vella Lavella, Guadalcanal and Bougainville.

His postwar assignments included duty as a student and an instructor at various interservice schools and as commandant of the Marine Barracks at 8th and I streets SW in Washington. He was promoted to brigadier general upon his retirement there in 1956.

Gen. Williams, who maintained a residence in Washington from 1959 until his death, was born in Arbor Vitae, Wis. He graduated from Ohio State University in 1929 and was commissioned in the Marine Corps. Before World War II, he served with the famed 4th Marines in Shanghai.

After his retirement, he earned a master's degree in political science at the University of Wisconsin and then became a consultant on military affairs. He was a senior researcher at the Brookings Institution, a consultant to the Defense Department and an official of the Research Analysis Corp. His work took him to Vietnam, Thailand and Iran to study counterinsurgency warfare. He retired in 1970.

Gen. Williams was the author of numerous articles published in professional journals. His also wrote "The Old Corps: A Portrait of the U.S. Marine Corps Between the Wars," which was published last year by the Naval Institute Press.

Gen. Williams was a member of the Metropolitan Club, St. John's Episcopal Church, Lafayette Square, and the Washington Cathedral Association.

Survivors include his wife, the former Alice Tuckerman, of Wisconsin and Washington, and two daughters, Edith Tuckerman Williams and Sarah Fenno Williams Lord, both of Baltimore