Nothing happens in a vacuum. The story of the Allied POWs who were forced to build the TBR can only be understood in the context of the war across the SouthEast Asian region.
Within days of the attack on Pearl Harbor, the IJA invaded Malaya via Thailand targeting the “impregnable” garrison on Singapore. Only a few weeks later, on Feb 15th 1942, Singapore fell. The IJA found itself in possession of over 100,000 Allied POWs. These consisted of mainly British troops with some Australian and Indians as well. A few weeks later, on Mar 8th, the Dutch authorities capitulated on the island of Java adding thousands more Dutch, Australian and American POWs.
Next the IJA invaded Burma with an eye towards pushing the British out of India. This, however, proved to be ‘a country too far’. Not only did the Japanese advance bog down but supplying the army in Burma became problematic. Allied planes and submarines found it easy to sink supply ships sailing along the Andaman coast from Singapore to Burma. Seeking a more secure overland route, Japanese Engineers dusted off an earlier British plan and decided to link the extensive rail systems of Burma, Thailand and Malaya. This would require a 415 kilometer-long rail link crossing the Burma-Thai border. The British had estimated it would take 4-5 years to build. The IJA Engineers said they could do it in less than 2 years!
In Jun 1942, they transferred the first of 61,000 Allied POWs from Singapore to NongPlaDuk Thailand to begin that rail link. This workforce would be joined by hundreds of thousands of Asians known to the Japanese collectively as the romusha. Australian, Dutch and American POWs were sent from Java to Singapore then on by what were known as Hellships to Burma. Almost daily, trains from Singapore carrying their cargo of POWs arrived at the transit camp at BanPong Thailand. These were mainly British POWs. Later, Australian, Dutch and American POWs were sent there from Java via Singapore.
Construction proceeded in both directions working towards a meeting place at Konkoita in Thailand. The 5th Railway Engineer Regiment oversaw about 11,000 Allied POWs and tens of thousands of Burmese romusha working east from Thanbyuzayat. In Thailand, the remainder of the Allied POWs plus hundreds of thousands of romusha were to construct the longer portion (over 300 Kms), overseen by the 9th Regiment. The 9th established its HQ at the walled city of Kanchanaburi once the initial 50 Km section of rails were lain by contract Thai workers starting at NongPlaDuk.
In the most general terms, both sectors of the Railway began in Lowlands regions of generally flat unobstructed terrain. Construction proceeded rather easily. But on either side of the border, the terrain was much more mountainous and foreboding, consisting of uninhabited virgin jungle. In the Thai Sector, between these two was a transition area of rising terrain known as Hintok that was to present an engineering challenge.
As more men arrived and more camps were established farther from the supply sources, the condition in these jungle camps deteriorated rapidly. The logistics system meant to supply them was utterly incapable of meeting the needs. While the conditions in the Lowlands camps was not good, it was infinitely better than those farther along. Malnutrition gave way to starvation. The men were afflicted by multiple diseases such as malaria, tropical ulcers and dysentery – usually simultaneously. Then came the monsoon rains. The conditions in the Allied POWs camps went from bad to horrendous; that in the romusha camps was dire! In April-May-June, an outbreak of cholera swept through the Highlands camps just inside the Thai border. Hundreds of Allied POWs died. The 7000 men of F Force suffered a 40% death rate with cholera claiming many. Bereft of the organization and discipline of the military structure, the Asian Forced Laborers died by the tens of thousands!
The military officers kept detailed accounts of the causes of death and burial places of their charges. The romusha were cremated in huge pyres and when there was no one left to light the fires, they were left where they died. No one counted them; no one buried them; no one mourned them. POW work parties were sent to burn these camps and their inhabitants – not all of whom were as yet dead!
Via a superhuman — some would say inhumane – effort the Railway was completed in Oct 43 in just 15 months. However, the projected delivery rate of 3000 tons of materials per day was never achieved. Best estimates are that no more than 1000 tons was ever carried in any one day.
In 1944, Allied bombers began attacking the system on a regular basis. Bridges were the easiest targets to identify if not hit. The largest of these were the wooden and iron bridges crossing the Mae Klong River near Kanchanaburi. This Bridge would later be made famous by the purely fictional book and movie: Bridge on the River Kwai. There is definitely a real Bridge (two in fact although the wooden one was torn down post-war), but there never was a River Kwai! In Jun 45, both of these bridges were damaged beyond repair and the TBR ceased to function. Due to the inaccuracy of the bombing in that era, many POWs were killed by friendly fire when bombs fell into their housing areas in camps near the targets.
Following the completion of the Railway, the POWs and romusha were consolidated to a series of camps at Kanchanaburi. Diet and overall conditions improved greatly – at least for the POWs. Life was not so kind to the romusha. Both groups continued to suffer the effects of the maladies they had encountered in the work camps. In April 44, a true hospital was established in the nearby town of Nakorn Pathom. The treatments available there saved many POW lives. The romusha were afforded no such luxury! With tens of thousands of them crammed into squalid huts, they continued to die by the day. No one cared! We simply have no accounts of what daily life was like in those camps. Eye witnesses describe how in the ‘hospital’ (read death camp) adjacent to the largest romusha camp, a grave would be dug every morning then all who died that day would be tossed in. The hole would be closed that evening and this process repeated day after day for months. While the Allied POWs were quickly evacuated at war’s end, the romusha languished for many months to come. In the 1950s, hundreds of these graves were unearthed as the road and surrounding area were developed. As many as 10,000 (or more) remains were placed in a common, unmarked grave near the military war graves cemetery. In 1991, hundreds more sets of remains were excavated at another nearby site. Most of those were carted away by a Thai-Chinese Charity organization and cremated before reburial in Petchburi. It is thought that these were the romusha who worked the Kra Isthmus and Mergui Road projects that followed the TBR in 1944, but this remains speculation.
In the late 1950s, about 130 km of the railway from NongPlaDuk to Tarsao (today called NamTok) were rehabilitated and daily trains carry tourist over the actual route of that small portion of the TBR. Along the way they cross the famous iron bridge then pass through a series of ‘cuttings’ through the limestone outcroppings that blocked way. They cross the 400m viaduct that clings precariously to the WangPo cliff side. Gone are the work camps that dotted this route. Gone are the temporary graves of the men who died there. Gone is the memory of the misery they endured. The NamTok station is before the other major tourist stop at HellFire Pass. This area has been claimed by the Australians as a memorial to their countrymen who worked the TBR.
Immediately post-war, teams of Australian graves searchers combed the jungles. Using maps and records kept by the military officers, they recovered the majority of the 12,000 POWs. These were then reburied in three war graves cemeteries – two in Kanchanaburi and one in Burma. No one looked for, no one recovered nor reburied the romusha!
Today, tourists flock to the Kanchanaburi area drawn by the lure of the River Kwai Bridge. Most have no concept of the true story of horror behind it and the associated railway.
 Although the Dutch army on Java (known as the KNIL) was composed of both European-born and Eur-Asian Dutch and native Javanese conscripts, the POWs were speak of belonged to the former group. The natives were quickly separated from their European counterparts.
 The Americans barely constituted 1% of all the Allied POWs who worked the TBR.
 The most oft quoted number is 250,000, but the full number is likely closer to a half million.