One of the most spectacular set pieces in the allegations against Gilles de Rais is the ferrying of forty decaying cadavers downriver, from Champtocé to Machecoul, for cremation. Bossard paints a delightful picture of this episode, with the barge waiting under the willows; Prouteau sardonically calls it a barque dantesque. In the prosaic words of the trial record, we merely have Henriet remarking that the remains were transported "by water".
The reasons for this Gothic journey need not detain us long. Gilles was about to hand the castle of Champtocé over to the Duke of Brittany; for complex political reasons, this could only be done by pretending to take it by force from his brother, who was currently occupying it. The token army of about twenty men was accompanied by the Chancellor of Brittany, Jean de Malestroit, presumably to oversee the handover. So everything that took place happened with Gilles' future judge on the premises, an embarrassing fact that is often glossed over.
None of this is disputed, although the date is unclear. Most commentators have it as June 1438. So in all probability, the Dantean barge processed down the Loire with its cargo of dead children at the height of summer, when nights are short and days long. Note too that Machecoul was supposedly taken by René de la Suze in November 1437; there is no record of how or when Gilles reclaimed it.
Now, René de la Suze had been living at Champtocé since October of the preceding year, so obviously the bodies were hidden in a reasonably safe place. For some reason, however, Gilles feared that they would be uncovered by Jean V, so it became necessary to exhume and dispose of them. They could hardly be burned on the spot - remember, the Bishop of Nantes was there and might have noticed. Hence the lengthy process of exhumation and the long journey to Machecoul, which could not be reached by river, so the final part had to be overland. Given the time of year, not all of this process could have been accomplished under cover of darkness.
The bodies were packed in one or two chests (accounts vary) and were burned at Machecoul. Apparently nobody in the castle or the village noticed the stinking smoke that must have resulted. Note that much is made, during the trial, of how the bodies were burned immediately. How a backlog of forty was allowed to build up under a tower at Champtocé, dating back to around 1432 presumably, and nobody ever noticed are questions which are not addressed.
Gilles de Rais himself was supposed to have accompanied the remains on their final journey, since he was not a man to miss out on inhaling the stench of burning bodies. We are not told how his guest, Jean de Malestroit, felt about being left to entertain himself while his host was mysteriously absent for a period of many hours. Hospitality was important and Gilles' behaviour would have been seen as unspeakably rude.
The events at Champtocé have an exact parallel at Machecoul in October of the preceding year. When he heard that René had taken Champtocé, Gilles panicked and had (again) around forty bodies exhumed and cremated. None of this is plausible, as Gilles never before or after displayed any fear of the brother who was by far his military inferior, but at least on this occasion there was no need for an excursion by river. The two episodes are so similar that many biographers confuse or deliberately conflate them.
Gilbert Prouteau boggled at the sheer unlikelihood of the mass transportation of so many decomposed corpses by river and land over a distance of 111.4 kilometres (nearly 70 miles). Nous passons encore une fois les frontières de la vraisemblance [Once more we go beyond the bounds of credibility], he remarked, and it is hard to argue with him.