Engaging a determined enemy across a broad range of conditions, the U.S. Army in World War II's Southwest Pacific Area (SWPA) played an important role in the defeat of Japan. How units fought and learned in SWPA and how they adapted to the evolving challenges of their environment is the focus of this dissertation. The subject remains largely unexplored, especially in contrast to the attention the European theater has received. An examination of the 112th's performance not only illuminates an understudied area in the historiography of World War II but also offers relevant lessons for contemporary military organizations. Mining a rich collection of primary sources, this study analyzes the development of the 112th Cavalry Regiment and sheds light on how American units in SWPA prepared for and conducted combat operations. A National Guard unit federalized in 1940 and sent to the Pacific theater in 1942, the 112th performed garrison duties on New Caledonia and Woodlark Island and eventually fought in New Britain, New Guinea, and the Philippines. Before deactivating, the regiment also served in Japan during the first months of the occupation. Concentrating on one unit illustrates the extent to which ground forces in SWPA were driven to learn and adapt. The 112th had mixed success when it came to carrying out its assigned missions effectively. The same was true of its efforts to learn and improve. The unit's gradual introduction to combat worked to its advantage, but learning was not simply a matter of building on experience. It also involved responding to unexpected challenges. Experience tended to help, but the variety of circumstances in which the cavalrymen fought imposed limits on the applicability of that experience. Different situations demanded that learning occur in different ways. Learning also occurred differently across the organization's multiple levels. Moreover, failure to learn in one area did not, as a matter of course, undermine advancement in all. Much depended on the presence of conditions that facilitated or disrupted the learning process, such as the intricacy of the tasks involved, the part higher headquarters played, and the enemy's own responses to the changing environment.

Master of Arts / Department of History / David A. Graff / On December 7, 1941 the Japanese Empire launched a surprise attack on the United States at the Pearl Harbor naval base in the territory of Hawaii. The following day President Franklin D. Roosevelt declared war on Japan, and America was suddenly an active participant in a global war that had already been underway for over five years. World War II pitted the Axis (Japan, Germany, and Italy) against a coalition of allied nations that were united primarily by fear of Axis totalitarianism. Typically referred to as the Allies, the alliance’s most powerful participants included the United States, the Soviet Union, and Great Britain. However, many other nations were involved on the Allied side. Smaller European countries such as Holland, Belgium, and Poland fought with armed forces and governments in exile located in London after their homelands had been overrun by the Germans in 1939 and 1940. China had been at war with Japan since 1937. After the United States entered the war, allied action resulted in the creation of different, localized military coalitions between 1941 and 1945. These coalitions presented Allied leaders with unique problems created by the political, geographic, military and logistical issues of fighting war on a global scale. The earliest coalition in which the United States was involved was known by the acronym ABDACOM, short for the American, British, Dutch, Australian Command. ABDACOM’s mission was the defense of the Malay Barrier, which stretched from the Malay Peninsula through the Dutch East Indies to New Guinea, and the protection of the Southwest Pacific Area from Japanese invasion. In its brief two-month existence the ADBA coalition in the Southwest Pacific Area failed to prevent the Japanese from taking the Malay Barrier, Singapore, Burma and the islands between Java and the Philippines. This was due not to one overriding problem, but to a combination of planning, command, and logistical problems, compounded by the distance of Allied production and training centers from the front lines. These problems can be traced from the late 1930s to the dissolution of ABDACOM at the end of February 1942. Historians have often overlooked the underlying causes of the United States’ first foray into coalition warfare in World War II. To better understand why the Allied forces succumbed to the Japanese onslaught so quickly, one must look at political, military and economic relations between the United States and its allies prior to the onset of hostilities in 1941. Domestic political realities combined with international diplomatic differences kept the United States from openly preparing for coalition action until the Japanese attack on Pearl Harbor. The ensuing military coalition suffered from numerous deficiencies in command structure and logistics. Though pre-war planning existed within each of the Allied governments, the lack of cooperative action gave the Japanese military an insurmountable military advantage over the members of the ABDA coalition. Given the limited scope of this paper the focus will be on American participation in ABDACOM. The other countries involved will be included insomuch as they help to fill out the story of the United States and its first coalition effort in World War II. The story of the ABDACOM coalition is one of perseverance, creative planning, and deep stoicism in the face of overwhelming odds. The short life of the coalition gave planners in Washington, D.C. and London time to sort out potential conflicts between the Allies.

The Chatham Islands are located in the SW Pacific Ocean, approximately 850 km to the east of the South Island of New Zealand. This small group of islands is situated near the eastern margin of the Chatham Rise, an elongated section of submerged continental crust that represents part of the Late Paleozoic-Mesozoic Gondwana accretionary margin. The location and much of the geology of the Chatham Islands are attributed to intra-plate basaltic volcanism, initiated during the Late Cretaceous, in association with development of a failed rifting system to the south of the Chatham Rise. Despite the volcanic nature of much of the geology, the majority of the Cenozoic sedimentary stratigraphic record on the islands comprises non-tropical skeletal carbonate deposits whose deposition was often coeval with submarine volcanics and volcaniclastic deposits. This has resulted in complex stratigraphic relationships, with the volcanic geology exerting a strong influence on the geometry and distribution of the carbonate deposits. These limestones, despite some general field descriptions, have been little studied and are especially poorly understood from a petrographic and diagenetic perspective. The carbonate geology in detail comprises eleven discrete limestone units of Late Cretaceous through to Pleistocene age which were studied during two consecutive field expeditions over the summers of 2005 and 2006. These limestone occurrences are best exposed in scattered coastal outcrops where they form prominent rugged bluffs. While many of the younger (Oligocene to Pliocene) outcrops comprise of poorly exposed, thin and eroded limestone remnants (it;5 m thick), older (Late Paleocene to Early Oligocene) exposures can be up to 100 m in thickness. The character of these limestones is highly variable. In outcrop they display a broad range of textures and skeletal compositions, often exhibit cross-bedding, display differing degrees of porosity occlusion by cementation, and may include rare silicified horizons and evidence of hardground formation. Petrographically the limestones are skeletal grainstones and packstones with a typical compositional makeup of about 70% skeletal material, 10% siliciclasts, and 20% cement/matrix. Localised increases in siliciclastics occur where the carbonates are diluted by locally-derived volcaniclastics. The spectrum of skeletal assemblages identified within the Chatham Island limestones is diverse and appears in many cases to be comparable to the bryozoan dominant types common in mainland New Zealand and mid-latitude Australian cool-water carbonates in general. However, some key departures from the expected cool-water carbonate skeletal makeup have been identified in this study. The occurrence of stromatolitic algal mats in Late Cretaceous and Early Eocene carbonate deposits indicates not cool-temperate, but certainly warm-temperate paleoclimatic conditions. A change to cool-temperate conditions is recorded in the limestone flora/fauna from the mid-Late Miocene times following the development and later northward movement of the Subtropical Front. An uncharacteristic mix of shallow-shelf (bryozoans) and deeper water fauna (planktic foraminifera), together with their highly fragmented and abraded nature, is indicative of the likely remobilisation and redistribution of carbonate, primarily during episodic storm events. The Chatham Islands limestones formed within the relative tectonic stability of an oceanic island setting, which was conducive to ongoing carbonate accumulation throughout much of the Cenozoic. This contrasts markedly with other mainland New Zealand shelf carbonates which formed over sporadic and short-lived geological periods, experiencing greater degrees of burial cementation controlled by a relatively more active tectonic setting. As a consequence of the tectonically stable setting, the Chatham Islands limestones have experienced little burial and exhibit a paucity of burial cementation effects. They remain commonly soft and friable. Detailed petrographic investigations have shown the limestones are variably cemented by rare uneven acicular spar fringes, poorly to well-developed syntaxial rim cements about echinoderm fragments, and equant/blocky microsparite. Staining of thin sections and cathodoluminescence petrography show these spar cement generations are non-ferroan and their very dull- to non-luminescent nature supports precipitation from Mn-poor oxygenated waters, likely of an either meteoric or combined marine/shallow burial origin. Micrite is the dominant intra- and inter-particle pore fill and occurs both as a microbioclastic matrix and as precipitated homogenous and/or micropeloidal cement. The rare fringing cements often seen in association with homogenous and/or micropeloidal micrite may be indicative of true early marine (seafloor) cement precipitation and localised hardground development. An interesting feature of the geology of the Chatham Islands is the occurrence of carbonate material within sedimentary dykes. The locations of the dykes are in association with volcanic and volcaniclastic deposits. Similarities between dyke characteristics at Red Bluff on Chatham Island with mainland occurrences from East Coast and Canterbury Basins (North and South Islands, respectively) on mainland New Zealand have been recognised. They show complex structures including sidewall striations, internal flow structures as revealed by grain sorting, and extra-clast inclusions of previous fill lithologies which are characteristic of carbonate injection. This is in contrast to other dykes which are known to be of a passive fill origin. Multiple phases of carbonate sediment injection can be recognised by crosscutting relationships enabling the determination of a parasequence of events. Possible injection mechanisms are most likely associated with sediment overloading or hydrothermal pressurisation associated with emplacement of submarine volcanics. The Chatham Islands provide an exciting example of a geologically unique and complex non-tropical carbonate depositional setting. The production of carbonates is controlled by volcanic and volcaniclastic sediment input with the types of carbonate deposits and water depth variations related to thermal uplift/subsidence in association with global eustatic sealevel and temperature changes associated with development of Southern Ocean water fronts from the Late Cretaceous-Cenozoic. Carbonate deposition on the Chatham Islands is considered to relate to a rather variable and small scale oceanic, high energy, cool-water carbonate ramp setting whose geometry was continually evolving/changing as a consequence of periodic volcanic episodes.