At the outbreak of the World War II, Bare served at the Marine Barracks Quantico, Virginia, and remained there until October 1942, when he was transferred to San Diego, California as operations officer (G-3) of the Amphibious Corps, Pacific under Major General Holland Smith.

Another important assignment came in June 1943, when Bare was transferred to London and assigned to the staff of Naval Commander-in-Chief of the Allied Naval Expeditionary Force, Admiral Bertram Ramsay as staff officer for plans.
He participated in the planning of the Invasion of Normandy and later observed British Assault Force "J" attacking German forces near Courseulles-sur-Mer, incorporating his observations into his report.
He was later decorated with the Bronze Star Medal with Combat "V" for his service in this capacity.

Colonel Bare was transferred back to the Pacific theater in October 1944 and assigned to the staff of 1st Marine Division.
He participated in the final phase of the Palau Islands Campaign and succeeded Colonel John T. Selden as division chief of staff at the beginning of November 1944.
Bare was appointed to this capacity following the Battle of Peleliu, where 1st Division suffered heavy casualties.
New division commander General Pedro del Valle tasked Colonel Bare with the supervision of the re-equipping and training, which effected a virtual reorganization of the division.

Following five months of training, 1st Marine Division participated in the Battle of Okinawa at the beginning of April 1945.
Bare took part in the amphibious landing and following the deployment of his headquarters ashore, he coordinated divisional units until the end of the operation.
He distinguished himself again and was decorated with the Legion of Merit with Combat "V" for the training of the division and for his service during the battle.
At the outbreak of the World War II, Bare served at the Marine Barracks Quantico, Virginia, and remained there until October 1942, when he was transferred to San Diego, California as operations officer (G-3) of the Amphibious Corps, Pacific under Major General Holland Smith.
Another important assignment came in June 1943, when Bare was transferred to London and assigned to the staff of Naval Commander-in-Chief of the Allied Naval Expeditionary Force, Admiral Bertram Ramsay as staff officer for plans. He participated in the planning of the Invasion of Normandy and later observed British Assault Force "J" attacking German forces near Courseulles-sur-Mer, incorporating his observations into his report. He was later decorated with the Bronze Star Medal with Combat "V" for his service in this capacity.
Colonel Bare was transferred back to the Pacific theater in October 1944 and assigned to the staff of 1st Marine Division. He participated in the final phase of the Palau Islands Campaign and succeeded Colonel John T. Selden as division chief of staff at the beginning of November 1944. Bare was appointed to this capacity following the Battle of Peleliu, where 1st Division suffered heavy casualties. New division commander General Pedro del Valle tasked Colonel Bare with the supervision of the re-equipping and training, which effected a virtual reorganization of the division.
Following five months of training, 1st Marine Division participated in the Battle of Okinawa at the beginning of April 1945. Bare took part in the amphibious landing and following the deployment of his headquarters ashore, he coordinated divisional units until the end of the operation. He distinguished himself again and was decorated with the Legion of Merit with Combat "V" for the training of the division and for his service during the battle.
Robert O. Bare