Smith was a temporary colonel when the United States entered World War II in December 1941. In 1942, promoted to brigadier general, he served as an assistant division commander of the 76th Infantry Division, later becoming a major general and taking command of the 27th Infantry Division, the unit charged with the defense of the outer Hawaiian Islands. In November 1943, the 27th Inf. Div. was incorporated with the 2nd Marine Division to form the V Amphibious Corps for the purpose of invading and securing the Gilbert Islands in the Central Pacific. While the Marines took the major objective, Tarawa Atoll, the Army was tasked with capturing Makin Atoll approx. 120 statute miles to the north. The corps commander, Marine CorpsLieutenant General Holland M. "Howlin' Mad" Smith, expected the Army's 6,500 men to be able to overwhelm the 800 Japanese defenders in a day. Furious upon being informed of a lack of progress, Holland Smith went to Makin to assess the situation: "When he arrived at Ralph Smith's HQ he was told that there was heavy fighting in progress in the north of the island. Commandeering a jeep, he drove to the scene of the 'battle' and found it, in his words, 'As quiet as Wall Street on a Sunday.'... This incident was the catalyst for a serious breakdown in relations between the Marines and the army that continued until well after the war." Four full days were required to conquer Makin. In July 1944, the V Amphibious Corps, now including an additional Marine division, was assigned to the invasion of the Mariana Islands. In this action, Ralph Smith's division fought alongside the Marines in the hard struggle for the mountainous island of Saipan. During the fight for Mt. Tapotchau in the center of the island, a vast difference in training and tactics between the Marines and the Army led to the 106th Infantry Regiment failing to reduce the area known as "Hell's Pocket", thus falling far behind the advance line of Marines. The corps commander, already ill-disposed toward the 27th Inf. Div. because of its perceived lack of aggressiveness on Makin, relieved Ralph Smith of command and ordered him off the island. He contended that Ralph Smith's men had "failed to attack on time," unnecessarily costing Marine lives in the conquest of the island. Five times in the Pacific Theater of Operations were Army generals relieved of command, but it was unprecedented for the order to be given by a Marine Corps general, and the incident caused a considerable rift between the two branches. The Buckner Board, an all-Army panel that investigated the incident, concluded that, while Holland Smith had the authority to fire Ralph Smith, he had not acquainted himself with the particular difficulties faced by the Army troops in the fight for Mt. Tapotchau and that the firing was "not justified by the facts." Ralph Smith was given command of the 98th Infantry Division charged with the defense of the Hawaiian Islands, but the negative publicity associated with his firing on Saipan made it impractical for him to remain in the Pacific Theater. He was thus transferred to Camp J.T. Robinson, Arkansas, where he supervised the Infantry Replacement Training Center. Smith went on to serve as the military attaché at the United States Embassy in Paris and CARE's chief of mission for France. While he worked for CARE he also oversaw operations in other western European countries. Smith was decorated with the Legion of Merit for his service in World War II. Smith retired from the Army in 1948.
