I'm reposting someone else's question from 2018 because it got no traction and no replies and I have the same question!
Posted by
📷
In the second-to-last paragraph of FDR's 1941 State of the Union speech (better known as the Four Freedoms speech), given on January 6th, 1941, FDR says, "Since the beginning of our American history, we have been engaged in change - in a perpetual peaceful revolution - a revolution which goes on steadily, quietly adjusting itself to changing conditions - without the concentration camp or quick-lime in the ditch." A quick Google search showed that quick-lime is another word for Calcium Oxide, a compound that was used in ancient weapons and can cause severe irritation to the skin and when it reacts with water, it heats up. Also on Axis History Forum (https://forum.axishistory.com//viewtopic.php?t=23456), Ben Fanjoy writes, "In the account, he claims to have seen two death pits in which Jews were packed, alive, to the brim. On each "layer" of bodies, quicklime was sprinkled. He then said the SS hosed down the pit with water, in turn, turning the quicklime into a caustic substance, thus "boiling", as he put it, the victims.", so it could also have been used by the Einsatzgruppen in this way. Why would he reference "concentration camps" and "quick-lime" if news about the Holocaust only reached the US after Operation Barbarossa? Did he have knowledge of these events, or was he referring to another use of "concentration camps" and "quick-lime"? The Speech if you want to check: http://oppenheimer.mcgill.ca/IMG/pdf/Four_Freedoms.pdf
EDIT: The Axis History Forum post was about a section of a book called "Masters of Death: The SS-Einsatzgruppen and the Invention of the Holocaust"
This is one of those occasions where the answer is really very short and simple. The Nazi concentration camp system predated the Holocaust itself - it was almost as old as the regime itself, with camps used to manage undesirable populations (members of left-wing political groups, criminals, social 'deviants', Jews etc) from the early days of the regime, with the system waxing and waning in size and complexity during the 1930s and in response to political events and developments in the Third Reich. That these camps existed was no great secret internationally. What was not known at the time of FDR's speech - indeed, didn't yet exist at the time of FDR's speech - were the extermination camps, camps designed not to segregate undesirables or extract labour from them, but simply to kill them as speedily as possible, sites like Treblinka, which were so physically small that they couldn't actually house the prisoners they received (in contrast, Auschwitz was a hybrid camp that served to exterminate some and house others as a source of slave labour, which is why there were so many survivors). While extermination camps were indeed very secretive, the wider camp system wasn't - there were simply too many, and too many people passed in and out of them (including some who subsequently went into exile and spread word of their experiences in them). If you want to know more about the camp system as it existed before the extermination camps, Nikolaus Wachsmann's 'KL' has become the standard text on their history, and u/commiespaceinvader gives a good overview here.
The quicklime is even simpler - it's not a reference to a specific event or even a specific method of execution or torture, but rather quicklime's properties in aiding the decomposition of corpses, in particular preventing them from smelling when improperly buried. FDR is using this as a rhetorical device to refer to extrajudicial violence and killings, the kind carried out at night beside a road in secret, and which were a hallmark of fascist movements and regimes even before the outbreak of war.