Blood as a strategic resource: Lessons from Iwo Jima for civilian and military transfusion in large‐scale combat operations

Blood is a national strategic resource and the cornerstone of trauma resuscitation. In combat, the capacity to collect, move, store, and transfuse blood determines not only survival but operational tempo. As US forces prepare for prolonged large-scale combat operations (LSCO),1, 2 planners must anticipate casualty production far exceeding that seen in recent counterinsurgencies. LSCO is expected to take place in a multi-domain operations (MDO) threat environment. In these circumstances, blood logistics will face sustained demand, attrition, supply chain disruption, cyber interference, and extended evacuation timelines.2, 3 The 1945 Battle of Iwo Jima provides an empirical benchmark for sustained high-throughput transfusion operations under extreme casualty density. Unlike recent counterinsurgencies, Iwo Jima generated casualty production an order of magnitude higher,4, 5 sustained over 36 days,4 supported by globally coordinated donor mobilization and cold-chain distribution under austere conditions.6 At the time, this was part of the largest wartime Low-Titer Group O Whole Blood (LTOWB) distribution effort in US military history,6 and no known modern battle has approached the total volume of LTOWB delivered during Iwo Jima.7, 8 Its relevance to LSCO does not lie in replicating World War II clinical practice, but in demonstrating that a mature LTOWB system can sustain continuous throughput when subjected to intense, prolonged operational demand. Accordingly, this paper synthesizes wartime administrative records and official campaign histories to quantify the operational performance of the Iwo Jima transfusion system, emphasizing logistics rather than clinical outcomes. By defining what a fully mobilized wartime blood program delivered under sustained large-scale combat operations–level casualty density, this analysis establishes an empirically grounded benchmark for blood throughput and donor mobilization. That benchmark is then used to assess contemporary planning factors in the context of a modern blood system that must simultaneously support large civilian transfusion requirements and military operations. In doing so, this comparison highlights the gap between doctrinal resuscitation expectations and historically demonstrated surge capacity, and frames LTOWB availability as a potential strategic limiting factor in future LSCO rather than a solvable downstream logistical problem. This analysis relied on aggregate wartime administrative documentation rather than patient-level clinical data. A total of 74 sources were reviewed for inclusion, consisting of official archival compilations, campaign histories, contemporary articles, and 22 after action reports. Quantitative values were abstracted from three authoritative documentation sets: (1) the US Navy's Administrative History of the Medical Department in World War II,9 (2) official Marine Corps campaign histories including Iwo Jima: Amphibious Epic4 and Western Pacific Operations,10 and (3) Kendrick's Blood Program in World War II,6 which synthesized contemporaneous records from the joint blood distribution program. These compilations were derived from wartime medical documentation but are not original patient records. Where these sources cited primary source reports, they were sought through the National Archives, Naval History and Heritage Command, the US Marine Corps History Division, AMEDD historical collections, the Combined Arms Research Library, and other digitized federal repositories. Most of the key primary sources cited in these records that are relevant to this work appear no longer extant. All quantitative values were captured using a structured abstraction form developed for this study. Two authors independently researched the required data; when one author identified a quantitative value in a source document, it was recorded in the extraction log along with the citation. A second author then independently queried the cited document to verify that the value had been transcribed accurately and that the contextual interpretation was correct. The abstraction form included fields for casualty counts and personnel denominators, but its primary focus was blood-system variables: units received at each echelon, units processed and issued, documented transfusions ashore and afloat, discard volumes and causes, cold-chain characteristics, delivery modes, and timing of distribution within the operation. Discrepancies were resolved by consensus before inclusion in the final dataset. Personnel and casualty denominators were abstracted primarily from military history casualty appendices. Although minor variation between sources is well documented historically,11 most differences in this dataset were small and did not meaningfully alter derived values such as units per casualty. However, one exception was the treatment of the late-arriving garrison force. Although these personnel arrived after the initial assault and are excluded from force-strength denominators in some operational histories, they contributed a small but nonzero number of casualties included in aggregate casualty counts for the operation. To preserve internal consistency between casualty counts and total engaged strength, we included the garrison force in the denominator. This choice reduces the reported per-casualty LTOWB utilization but represents a methodologically consistent and conservative interpretation aligned with the structure of the underlying historical records. In all instances where multiple plausible values existed, conservative estimates were selected to avoid overstating operational intensity or transfusion throughput. All used documents are publicly available, digitized federal publications. No protected health information was accessed and institutional review board oversight was not required. The Battle of Iwo Jima lasted 36 days and involved approximately 111,308 US personnel, including 75,144 committed ashore.12 A total of 25,992 casualties (34.6%) occurred, including 6821 killed and 19,171 wounded, corresponding to 6.48 casualties per 1000 personnel per day.4 This sustained casualty density substantially exceeded that observed in modern conflicts. For example, the Second Battle of Fallujah (2004), one of the most casualty-intensive engagements of the Global War on Terror, produced approximately 0.52 casualties per 1000 personnel per day—roughly 12-fold lower.5 LTOWB support for the Iwo Jima operation was organized as a phased, integrated system spanning afloat resuscitation platforms, evacuation assets, and shore-based medical facilities.4, 9, 10 This architecture aligned transfusion capability with casualty flow, concentrating early transfusion support at sea during the assault phase and transitioning distribution ashore as the tactical situation stabilized. A mobile blood bank with organic refrigeration capability was embarked aboard a modified Landing Ship Tank (LST), LST-H 929 prior to the landings (Figure 1), and served as the primary forward distribution node during the early phase of the operation.9 From this platform, LTOWB was issued to other modified LSTs stationed about 2000 yards offshore,10 which received casualties directly from the beach and provided resuscitation and damage control surgery.9, 10 In functional terms, these vessels served a role analogous to modern Role II facilities.13 Additional LTOWB stocks were maintained aboard dedicated hospital ships operating offshore and at rear-area facilities supporting evacuation.9 As land-based facilities became established, the mobile blood bank was disembarked and reestablished ashore, where it functioned as the island blood bank and terminal distribution point for on-island care beginning on D + 8.9 Up to D + 22, it received 3994 units and issued 3569 units to battalion aid stations (Figure 2), regimental and division medical companies, and surgical sections.9 Across the entire operation, at least 5406 units of LTOWB were reported transfused ashore.4, 10 System-wide, approximately 12,600 units of LTOWB were used in the care of Iwo Jima casualties.4, 10 LTOWB supporting the Iwo Jima operation traversed a 7000-mile, multi-modal supply chain. Collection occurred at US West Coast donor centers in Los Angeles, Oakland, and San Francisco, with Oakland serving as the primary air point of departure.6 Bottles were refrigerated immediately after donation and then transported by Naval Air Transport Service aircraft along a staged Pacific route from Oakland to Oahu, Johnston Island, Kwajalein, Guam, and Saipan.6 Individual flight legs ranged from approximately 3 to 15 h, with cumulative air transit time to the Marianas typically under 48 h (Figure 3).6 Additionally, until February 1945, 25% of the blood used in the Pacific theater was purchased from the Australian Red Cross, although it is unclear to what extent this supported the Iwo Jima operation specifically.6 Following establishment of the Navy Blood Distribution Center at Guam, LTOWB was redistributed forward primarily by air. Before securing an airfield on Iwo Jima, LTOWB was flown by seaplane and landed offshore near Mount Suribachi, allowing direct aerial delivery to the objective area without reliance on maritime resupply.10 Once the land-based airfield became operational, fixed-wing aircraft replaced seaplanes for direct delivery to the island.10 The final aerial leg from the Marianas to Iwo Jima required approximately 3.5–4.5 h of flight time. Under favorable conditions, LTOWB could move from donor collection on the US West Coast to Iwo Jima within 2–3 days. Despite the effectiveness of the supply chain as a delivery system, maintenance of the LTOWB cold chain itself was a significant limitation. LTOWB was stored and transported in ice-cooled insulated containers (Figure 4) dependent on passive thermal buffering and periodic re-icing.6 Temperature monitoring at forward locations generally consisted of twice-daily checks, and quality control at the terminal ashore blood bank relied largely on visual inspection for hemolysis.6 Of 3994 units processed ashore, 18 (0.45%) were discarded for visible hemolysis attributed to thermal stress;9 however, this figure reflects only terminal handling losses and should not be interpreted as a comprehensive wastage or quality metric. Visual hemolysis is an insensitive indicator of cold-chain failure, and units experiencing subclinical temperature excursions or bacterial contamination would not have been detected under contemporaneous practices. Refrigeration methods, including ice-packed boxes, improvised shipboard storage, and partially buried shore installations,9 were necessarily ad hoc and vulnerable to heat exposure, handling delays, and combat disruption. Accordingly, it is true that the supply chain functioned incredibly well under the most extreme conditions, but maintaining the cold chain was a significant limitation. Survival at Iwo Jima should not be compared to modern clinical outcomes; the relevance lies not in outcome equivalence but in the demonstration that continuous LTOWB delivery was achieved at a scale unmatched in recent conflicts. Even excluding plasma and albumin, the volume of resuscitation fluid delivered in 36 days exceeded that administered by the busiest US combat support hospital in Iraq during the calendar year that included the Second Battle of Fallujah.7 US Office of the Joint Staff Surgeon planning factors, derived largely from counterinsurgency experience, estimate that approximately 20% of casualties will require transfusion with an average of eight whole blood equivalent (WBE) units.8 These projections are clinically appropriate for individual patient care and reflect current evidence-based practice. By comparison, the Iwo Jima transfusion system delivered 0.49 units per casualty, which was considered adequate for the era9 and was sustained without interruption despite unprecedented casualty density, austere logistics, and a contested supply chain. No data exist regarding what proportion of casualties were transfused on Iwo Jima. However, if one were to assume the same 20% factor present in current planning guidance,8 this would result in 2.47 units per transfused casualty, consistent with other published estimates of blood use in World War II.8 One modern contrarian source reports shortages of blood at Iwo Jima,14 but does not provide evidence supporting this claim, and it conflicts with contemporary subjective assessments which described “perhaps even excessive” use of whole blood.9 If modern military expectations are superimposed on Iwo Jima-level casualty production, the resulting LTOWB requirement would exceed 40,000 units.8 This exceeds not only the 12,600 units actually transfused during the battle, but also the peak sustained throughput achieved by the Pacific theater blood supply system in 1945.6 The implication is not that current targets are clinically incorrect, but that achieving them under LSCO would require a dramatically expanded donor base, agile mobilization strategy, and resilient forward storage architecture. This distinction has major strategic implications for national blood availability. In the modern United States, approximately 11.6 million units of whole blood and apheresis red blood cells are donated annually,15 a supply that supports routine civilian transfusion practice and cannot be reduced or paused during armed conflict. In contrast, during World War II the civilian transfusion footprint was extremely small. US blood banking began only in 1937,16 and civilian use remained limited throughout the war. As a result, wartime blood mobilization did not require balancing large-scale civilian demand against military requirements. That condition would be fundamentally different in large-scale combat operations today, where military blood demand would be additive to civilian need rather than substitutive. During the 6-month period from December 1944 through May 1945, US military blood shipments averaged approximately 60,788 units of LTOWB per month,6 reflecting sustained high-intensity operations across multiple theaters. Within this interval, blood utilization peaked in March 1945, when more than 76,000 units were shipped in a single month.6 When expressed relative to the modern US blood system, this sustained demand would represent approximately 9–10% of the current monthly type O blood supply,15, 17, 18 even under the restrictive transfusion practices8 of the era. When historical casualty volumes are scaled to modern WBE transfusion targets, the projected impact becomes substantially greater. Current damage-control resuscitation commonly targets about 8 units per transfused casualty, compared with approximately 2.5 units per casualty during World War II.8 Applying this scaling factor yields an estimated sustained requirement of more than 180,000 units of LTOWB per month, equivalent to 28% of the modern US monthly type O supply, with peak monthly demand reaching 35% of all type O units collected nationwide (calculations provided in Supporting Information Appendix I). LTOWB demand during World War II also occurred alongside large-scale plasma production. By the end of the war, of the more than 13 million pints of blood collected by the American Red Cross, over 10.3 million pints had been processed into dried plasma.6 This parallel demand underscores that even in World War II, LTOWB resuscitation did not occur in isolation, but alongside large-scale plasma production. As contemporary resuscitation doctrine increasingly explores early plasma use,19, 20 future military plasma requirements are likely to reintroduce a similar additional demand on the national blood system. Current published planning estimates suggest that the US military in a future large-scale combat operation could require approximately 10,080 units of LTOWB per month,8 a sobering figure, yet still substantially lower than what was demanded by a single 36-day battle during World War II, even when that battle was supported using far more restrictive transfusion standards than would be exercised in current practice. The United States has never attempted to sustain modern civilian blood donation requirements while simultaneously supporting LSCO-scale battlefield transfusion. Taken together, these data points indicate that LTOWB availability constitutes a binding national strategic resource in future large-scale combat operations, with the potential to constrain military operational endurance while simultaneously forcing adaptation within civilian transfusion practice under sustained wartime demand. The relevance of Iwo Jima to LSCO lies not in the clinical strategy of 1945, but in the operational surge capacity achieved by a fully mobilized transfusion system under sustained casualty density. That capacity depended on alignment of donor mobilization, long-range delivery, and distributed forward storage rather than on any single technological innovation. Whether comparable system performance can be achieved in the modern era, when military demand must compete directly with large civilian transfusion requirements, remains uncertain and represents a central strategic planning problem for wartime transfusion support. Develop LSCO surge estimates anchored in validated benchmarks and feasibility constraints. US military blood planning should incorporate empirically grounded surge projections and explicitly differentiate feasible operational support from ideal clinical targets, quantifying the resources required to close that gap. Establish national donor mobilization mechanisms before conflict. Civilian transfusion practice already exceeds the peak wartime donor mobilization achieved in World War II.6, 21 LSCO requirements will be additive rather than substitutive. Preconflict planning must therefore include scalable donor recruitment and collection systems that can be rapidly activated and sustained, rather than improvised after casualties appear. Synchronize military, civilian, and allied blood networks under shared standards. No isolated system can sustain LSCO-scale demand. Interoperable labeling, testing, and distribution standards are essential to allow blood to move across systems and borders without procedural bottlenecks. This coordination must be structured in advance, not developed ad hoc. Engineer cold-chain resilience with low-technology The cold used at Iwo Jima under contested LSCO planning should systems of operating without continuous or using distributed storage and procedural to resilience in an environment. This analysis is by the availability and of wartime medical blood bank and transfusion reports were not across and Marine Corps limiting and regarding transfusion or outcomes. In records not the distribution of transfusions relative to analysis of sustained utilization and of aggregate transfusion volumes over the 36-day operation. Where Marine Corps or Navy administrative compilations primary was as authoritative of contemporaneous these they not alter the aggregate throughput on which the of this are The documented performance of the Iwo Jima blood program must also be interpreted within the and of the era. and that are were in such as or were and therefore and cold-chain was using such as visual Accordingly, the should not be interpreted as evidence of clinical equivalence to modern transfusion practice, but rather as a demonstration of logistical throughput achieved under austere historical interpretation is comprehensive volume The Blood Program in World War remains the source on the the wartime transfusion effort close provides operational but Kendrick's work with contemporaneous Navy and Marine Corps medical records this but does not the authors of the military reports have been to operations in a these reflect one campaign within a theater of war. Although Iwo Jima provides documentation of sustained LTOWB transfusion under casualty density, regarding LSCO planning should be interpreted within this contextual This analysis establishes an empirically grounded benchmark for transfusion surge capacity under sustained LSCO casualty density and it within the of a blood system. When against that contemporary planning a that cannot be by medical doctrine but of donor mobilization, and before In this Iwo Jima is no longer a historical but a that LTOWB availability as a strategic of LSCO feasibility rather than a in wartime The authors to the of the for of primary source as well as the of the US Navy of and the National and and the US Marine Corps History for and to the original wartime records that this analysis The authors also for all and allied in the Battle of Iwo Jima, to to survival on future The authors have no conflicts of The data that support the of this are in the Supporting Information of this Supporting The is not for the or of any supporting information by the than should be to the corresponding author for the