Struggles on Saipan (23 JUN 1944)
On June 23, 1944, Maj. Gen. Ralph C. Smith’s 27th Infantry Division launched a hasty attack against the Japanese on the island of Saipan. Facing difficult analytical conditions, Lt. Col. William M. Van Antwerp, Smith’s capable G-2, was unable to provide significant intelligence on the enemy situation.
In the months before the attack, General Smith and his staff had begun planning a campaign against the Marianas in the Central Pacific. With the division designated as the operational reserve, the staff had looked at possible employment against all three of the targeted islands: Saipan, Tinian, and Guam. In fact, when the division eventually sailed for the Marianas in June, it had more than twenty different contingency plans.
As the division readied for its deployment, Van Antwerp and his staff prepared for intelligence operations. A 42-year-old National Guardsman from New York, Van Antwerp had served as the division’s intelligence officer since its deployment to the Pacific and had participated in its operations in the Gilbert Islands. In planning for the next campaign, he was forced to spread his planning and analytical efforts over the large number of contingency plans. To conserve resources, he used a standardized intelligence annex that could later convert to be part of the field order without change. When available, he added intelligence studies on the three targeted islands as appendices to the various annexes. Being studies rather than estimates, these lacked the analytical rigor necessary for operational intelligence. Moreover, they were based on woefully poor estimates from theater and task force intelligence. For example, American planners estimated the strength of the Japan’s Saipan garrison between 15,000 and 18,000, when the strength was closer to 32,000.
After Smith’s division landed on Saipan between June 16–20, this initial miscalculation was difficult to overcome. One of Van Antwerp’s regimental S-2s noted:
The enemy generally did not employ tactics of battle for more than company size groups…[and] the enemy appeared to lose all cohesiveness and the warfare degenerated into that of medieval times, small groups fighting harassing action and often fading away during the night.
Furthermore, enemy unit identification proved challenging. Van Antwerp gave several reasons for this: most Japanese soldiers knew only their unit’s code number or their immediate commander’s name, and the Americans were unfamiliar with the complex organization of the enemy forces. In short, making overall sense of the Japanese defenses was tough.
When Lt. Gen. Holland Smith, the Marine commander of the Saipan operation, ordered the 27th Infantry Division to attack on June 23, he estimated that no more than 300 Japanese defenders were in the area. Unfortunately, the Japanese numbered more than 1,000 and were supported by tanks as well as artillery. The Marine divisions failed to mention the tanks when exchanging information. With limited opportunity to reconnoiter and “little information of combat value” from the Marines, Van Antwerp could only report the enemy situation as “Continued defense in caves and holes, using 75mm artillery, mortars, and machine guns.” The battle became a week-long slugfest up rugged terrain known as Death Valley.
Regrettably, aerial photography never reached its potential on Saipan. The two Marine divisions, moreover, never regularly provided their intelligence reports to their Army colleagues. Yet, over time, as Van Antwerp and his regimental S-2s became more attuned with the enemy situation, orchestrated their own reconnaissance and observation posts, and relied on their own interpreters, their intelligence improved significantly.
Article by Michael E. Bigelow, INSCOM Command Historian. New issues of This Week in MI History are published each week. To report story errors, ask questions, request previous articles, or be added to our distribution list, please contact: TR-ICoE-Command-Historian@army.mil.
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