Why are the exact death tolls of the Bataan Death March uncertain?

The exact death tolls of the Bataan Death March remain uncertain primarily because the Japanese military severely underestimated the number of prisoners they would capture and was entirely unprepared, both logistically and materially, to manage the tens of thousands of individuals taken into custody.1

Because the surrender occurred in groups of varying sizes across the Bataan Peninsula, the process of accounting for the captives was disorganized from the start. Prisoners were forced to march under brutal conditions, with many dying from exhaustion, disease, or summary execution along the route, while others were packed into unsanitary boxcars or held in the squalid conditions of Camp O’Donnell, where thousands more perished from starvation and illness. Due to the chaotic nature of these events and the lack of systematic record-keeping by the captors, historians can only provide estimates for the number of lives lost.1