World War II artefacts and wartime use of caves in Guam, Mariana Islands
D. Taboroši. Current address: Laboratory of Geoecology, Graduate School of Environmental Earth Science, Hokkaido University, N-10, W-5, Sapporo, Hokkaido, Japan. email: danko@ees.hokudai.ac.jp J. W. Jenson. Water and Environmental Research Institute of the Western Pacific, University of Guam, Mangilao, GU 96923 email: jjenson@uog.edu
When referencing this article, please use the following convention: Taboroši , D. & Jenson, J.W. 2002 .World War II artefacts and wartime use of caves in Guam, Mariana Islands Capra 4 available at – http://capra.group.shef.ac.uk/4/danko.html
Introduction News reports from Afghanistan during 2001-2002 have highlighted the role caves can play in warfare. The wartime use of caves, however, is not peculiar to this conflict. It has been suggested that caves were used as fortifications at least since the Neolithic times, and that some of the earliest evidence of emerging military command structure and tactics comes from Neolithic cave paintings (Ferrill, 1990). Man-made cave systems were used as bases for Jewish guerrillas fighting against the Romans in Palestine (Watson, 1996), and the Vikings used lava caves as hideouts (Ólafsson, 1993). In medieval Europe, limestone caves were incorporated into castles, such as Pembroke and Carreg Cennen in Wales, and were used for water supply, storage, and defensive purposes (Fry & Lyons, 1997). During the American Civil War, caves were the foremost source of potassium nitrate for the production of gunpowder (Whisonant, 2001). Perhaps the most extensive use of natural caves in warfare in recent times occurred in World War II, when caves on islands throughout the Pacific were involved in many aspects of the war. This article is a summary of the wartime use and associated artefacts in the caves of Guam and the neighbouring Rota, Tinian, and Saipan, part of the Commonwealth of the Northern Mariana Islands (CNMI), in the western Pacific. Geology of Guam Guam, the largest and southernmost of the Mariana Islands, is an elongate island, 550 km 2in area, 48 km long, 6-19 km wide (Fig. 1). It is divided into two major physiographic provinces: southern Guam, a rugged volcanic
highland with some limestone outliers, and northern Guam, an undulating limestone plateau with two volcanic inliers. There are hundreds of caves on the island, mostly in the Plio-Pleistocene Mariana Limestone, a reef and lagoonal deposit that covers nearly all of the northern plateau and the eastern flank of southern Guam; and the Miocene Alifan limestone, a reef deposit, which caps much of the mountain ridge running along the western edge of southern Guam. The caves in these units belong to four general categories: pit caves, flankmargin caves, stream Fig. 1: Map of Guam and the Mariana Islands, showing caves, and sea caves. The locations mentioned in text principal publication on the geology of the island is a report with a 1:50000 scale geologic map by Tracey et al. (1964). The karst features of Guam are described in Mylroie et al. (2001) and a detailed inventory is provided by Taboroši (2000). History of Guam The Mariana Islands are thought to have been first inhabited between 5000 and 4000 BP. Spain colonised the islands after Magellan’s landing in 1521. The Spanish rule ended on Guam when the United States took possession in 1898, following the Spanish-American War. The island was administered by the US Navy until the Japanese invasion forces captured it on December 8, 1941. Liberated by the US on July 21, 1944, Guam was a restricted military area until 1962 (Rogers, 1996). Since the war, it has remained a territory of the US. Wartime Use of Caves There was extensive use of the caves on Guam in the years during, and following World War II. The caves were used primarily for defensive fortifications by the Japanese forces; water sources; places of refuge by
civilian population; and hiding places by Japanese stragglers following the war. The Japanese military forces excavated numerous artificial caves, which vary widely in extent, design, and engineering. They also modified many natural caves for wartime use. The man-made caves range in size from pits a few metres deep to intricate tunnel systems, usually hand-dug in natural escarpments by civilian forced labour (Fig. 2). The most accessible examples of this type are the tunnels in Hagåtña, Nimitz Hill, and Mataguac Hill. The interconnected caves located behind the courthouse in Guam’s capital, Hagåtña, have numerous entrances and were used as shelters for Japanese commanders. Similar tunnels on Nimitz Hill were used as a communication centre, and as the command post of General Takeshina, commander of the Japanese forces on Guam. Hand dug tunnels in a sinkhole on the southeast side of Mataguac Hill were part of the last Japanese command post on Guam, where General Obata, who had taken over after Takeshina was killed, and his staff committed ritual suicide in the final days of the battle. Natural caves also saw extensive wartime use and modification. Many were enlarged or connected to other caves, and walls, ceilings, and entrances were often reinforced by concrete. Most of such caves on Guam were part of the defensive fortifications installed to repulse the American invasion, and were typically converted into pillboxes and gun emplacements. Although many such caves were destroyed, sealed, or buried, during and after the war, numerous examples remain along the coast of Guam from Piti to Tumon Bay and on the ocean-facing slope of Nimitz Hill (MARS Inc., 2000).
Fig. 2: Entrances of hand-dug caves in Sumay, Orote Peninsula, Guam, with and without concrete-reinforced walls (entrances are about 1 m tall)
Coastal caves that intersect the freshwater lens were commonly used as water sources. Marbo Cave, on the Pacific side of northern Guam, for example, was used by the Japanese Army from 1942 to 1944, and by the
U.S. Army from 1947 to 1950 (Randall and Holloman, 1974). It contains a large concrete platform, which provided a base for an electrical water pump. Another example is the Tarague Natural Well #4, a vertical-walled collapsed cenote located on Andersen Air Force Base, in northern Guam. It was used by the U.S. military following the war, and contains a concrete platform and housing for the now defunct water pump. Caves were also used as places of refuge and as living quarters for the civilian population (Fig. 3) and some exhibit remarkable modifications. A large, 40-m deep cave in Tinian known to have been used by Okinawan civilians during the American bombardment of the island in 1944, contains 105 constructed features, including walls, enclosures, overhangs, cupboards, walkways and stairs, all made of rock (OEESC Inc., 2001). The famous Guma'Yu'os Cave (House of God in the local Chamorro language) in the Togcha Gorge was used by the Japanese as a field hospital and by Chamorro civilians as a church, at separate times during the war. It contains a stone altar. Some caves (Tinta, Faha, and Fena caves) are sadly remembered as sites of mass executions of civilians by the Japanese forces in the waning days of the final battle for Guam.
Fig. 3: A Japanese family hiding in a cave on Saipan, found by U.S. Marine patrol on June 21, 1944. National Archives and Records Administration. 127-GR-11383266.
During the war, US Navy radioman George Tweed was accidentally left behind when the American forces withdrew. He was kept hidden by the local people in a fracture cave for two and a half years until the liberation of the island in July 1944. Following the war, thousands of Japanese stragglers retreated to caves throughout Guam and the Mariana Islands, leaving most of the artefacts that are found today. Caves in the remote cliffs of northern Guam and deep in central southern Guam were used for many years following the war. The last Japanese straggler of the war, Sgt. Shoichi Yokoi was found hiding in a cave in southern Guam on January 24, 1972, twenty-eight years after the war ended.
World War II artefacts found in caves World War II artefacts commonly found scattered or concealed in caves in Guam and the Mariana Islands include helmets (Fig. 4), radios, batteries, canteens, gas masks and gas mask canisters, shoe parts, metal and porcelain bowls (Fig. 5), scraps of metal, ceramic fragments, eating utensils (Fig. 6), tea pots, beer, sake, medicine, and soy bottles, and toothbrushes.
Fig. 4: Japanese helmet left on a stalagmite in Kettle Cave.
Fig. 5: Japanese ricebowls bearing the Imperial Navy seal on the bottom, Kettle Cave, Saipan
Fig. 6: Travertine-encrusted kettle in Kettle Cave, Saipan.
Fig. 7: Machine gun bullets on belt (probably US .30 cal), Japanese glass bottles, and a human bone in Awesome Cave, Mt. Santa Rosa, Guam
Ordnance found in caves is generally limited to small, portable items that could be transported to a firing position nearby or were a part of personal armaments (Fig. 7). The most common types of Japanese bullets are 8 mm (for Nambu, Type 14, and Type 94 pistols), 9 mm (for Type 26 pistols), 6.5 mm (for Type 38 and 44 rifles), and 7.7 mm (for Type 2, 92, and 97 rifles). The bullets can come in clips of 5 rounds for rifles and light machine guns, and feeder clips of 30 rounds for heavy machine guns. Ordnance includes 58 mm Type 89 Mortars and 20 mm, 37 mm, 47 mm, and 57 mm AntiAircraft Projectiles, and Type 97 Hand grenades. Common American bullets and ordnance include .30 cal and .50 cal rifle and machine gun bullets, .38 cal and .45 cal pistol bullets, and MKII hand grenades, but are not often found in caves. In the recent years, ordnance and other World War II artefacts have become uncommon in caves on Guam, but are still ubiquitous in caves on Saipan, Rota, and Tinian (Fig. 8).
Fig. 8: Map of chambers 2 and 3 of site TN-1/2/51121 on Tinian, CNMI, from report by Gosser et al. (2001). Note the numerous artefacts and ordnance, paved area, constructed walls, and rock piles. The numbered features are mostly constructed rock platforms, containing World War II artefacts and human remains.
There is evidence that some caves were booby-trapped. A cave in Rota was found to contain numerous strategically placed boreholes filled with
picric acid, a highly sensitive bulk explosive detonated by heat, shock, or friction, whose trigger mechanism has deteriorated. Finally, human remains are now rarely found in caves. In the three decades following the war, formal bone-collecting missions were organized by Japanese veteran groups and the Governments of Guam and the CNMI, and most human remains were repatriated to Japan. Since then, bones that are still found may be turned over to the Japanese Consulate. Discussion Caves in Guam and the Mariana Islands, having seen extensive use in World War II, exhibit a range of modifications for wartime use and contain important artefacts. Common in the decades following the war, World War II artefacts are being actively removed from caves by amateurs. So far, there have been no island-wide comprehensive archaeological surveys, and published materials focusing on the World War II archaeology of caves on Guam are rare. Archaeological work on the island is typically carried out by contracted companies as part of environmental impact investigations. Unpublished reports resulting from such work and pertaining to specific sites can be found at the Micronesian Area Research Center at the University of Guam, the Historic Preservation Office at the Environmental Department of COMNAVMARIANAS (U.S. Navy on Guam), and the Historic Resources Division of the Government of Guam’s Department of Parks and Recreation. Acknowledgements We wish to express our appreciation to Brett Wallace, a military trained explosive ordnance disposal (EOD) technician, for identifying bullets and ordnance and reviewing the manuscript. Jennings Bunn, historic preservation officer and staff archaeologist for the Environmental Department of COMNAVMARIANAS, has been an active source of information regarding archaeological studies and reports. David Lotz of Guam Department of Parks and Recreation generously shared his knowledge on wartime use of caves. References
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