I deal with formerly classified documents pretty much every day. Government secrecy makes the terms "missing" and "destroyed" a little tricky to use, because they may be effectively missing and destroyed to most historians, but in reality they are often just being denied to us. Some secret documents do go missing, however, because they get misplaced or misfiled within the gargantuan government bureaucracy that at one point was trying to keep them secret, even if they no longer contain secret information in them. In fact, when it comes to secret documents, being misplaced is more common than being destroyed, because legally you cannot detroy secret documents without leaving a large paper trail — so that means that the documents are usually preserved, if anyone can figure out where they are preserved.

Anyway, on my blog not too long ago I wrote a series of very long posts about my hunt for, eventually success at finding (through unorthodox archival practice), and frustrations with declassification, regarding the legendary unredacted copies of the security hearing of J. Robert Oppenheimer. Here is the link to part I, where I describe why I started looking for them and how I found them. Here is the link to part II, where I analyze the new transcripts for what they do (and don't) tell us about the Oppenheimer case.

Separately, a few years back I wrote about a case where the US government "lost" about 4 million pages of secrets through misfiling. It happens more often than one might think, if one thought (erroneously) that the US government was very good at keeping track of large amounts of historical paperwork (it is not).

I wouldn't say it's destroyed (yet), but a lot of Phil Weigand's data is unpublished. Things like aerial photography from before agriculture became more intensive. Locations of looted shaft tombs and guachimontones. Profile drawings of looters pits in structures and tombs. Samples of ceramics from these looted sites. Even drawings of the sites he visited which were sometimes just sketches. His wife currently has all this data as far as we know, but she's not willing to let anyone look at it or see it unless you are going to enshrine Phil in the process. It's a shame, really. He was collecting data since the late 60s up until his death in 2011. We may never fully recover all the data he collected.

As an archivist, it pains me to admit this, but sometimes humanity’s records don’t survive.

My reasoning for suggesting this topic is was to talk about an instance where missing documents can actually be a good thing, in some sense.

I'm talking about the mountains of documents about Chinese immigration which were destroyed during the 1906 San Francisco Earthquake. On the one hand, these documents would have been invaluable resources for quantitative historical research on early China-to-U.S. immigration of Chinese people. However, the destruction of the documents made life easier for a lot of Chinese people.

Since corroborating documents were all destroyed, Chinese people living in the U.S. that claimed to be natural citizens essentially had to be taken at their world by the federal government. While I can't find an academic citation for this number, I've heard it claimed that if everyone who came forward as a natural citizen actually was, it would have required every Chinese woman to give birth to 800 people. At any rate, it was a widespread phenomenon, allowing Chinese immigrants the ability to secure a lot more rights, all possible only because of the destruction of a massive stack of documents.

This all had a trickle-down effect to--with so many Chinese claiming natural citizenship, they were then able to import their children. Oftentimes these didn't end up actually being "their" children, I've written on the 'paper sons' phenomenon before. The gist is that Chinese-American citizens would sell native Chinese children the right to claim they were the Chinese-American person's children, and thus have a chance at immigrating to the U.S. that way.

Lord knows how many fewer Chinese citizens the U.S. would have had in the early 20th Century if it hadn't been for that fateful destruction during the 1906 San Francisco earthquake.

18 and a half minute gap in the Nixon tapes . . . .

EDIT: Seriously though, the closing of the Chicago Municipal Reference Library is tragic not only for historians of the city but for historians of America. Though much was shifted to the Harold Washington Public Library, documents lost include:

The only collection of documents from other taxing bodies in Cook County, municipal codes pre-dating the 1871 Chicago fire, census information from 1890 to the present, original bids and contracts on construction of the airport transit systems, city planning documents, five-year plans for capital improvements, annual reports from every city department, maps of most underground conduits and above-ground airways, two million clippings from all daily newspapers in the area and 23 community and ethnic newspapers.

Wahhhhhhhhh. For the deets: http://www.chicagoreader.com/chicago/the-late-great-municipal-reference-library/Content?oid=887378

A number of the papers and documentation related to Anne Boleyn's trial, and that of her brother George and the other four men charged with adultery, are missing or destroyed. For example, no record remains the deposition Jane Boleyn, George's wife, apparently gave, which was a large part of the Crown's evidence against George and Anne.

With so much of the trial documentation missing, we still don't conclusively know whether Anne was guilty of some or all of the charges laid against her, though most historians now lean towards her innocence. (In contrast, Katherine Howard, Henry's fifth wife and Anne Boleyn's cousin, was almost definitely guilty of adultery on the face of the evidence.)

i do a lot of work in the history of islam in america and we lack a ton of valuable documents for most groups that started before 1950, especially african american groups.

I'd say some of the biggest things that scholars would want are:

A) any writings connected to W.D. Fard, the founder of the Nation of Islam (a few of his supposed letters are circulating, though). I think number one on his list would be a book that police found and that was supposedly written by him, entitled "the bible of islamism". Also, it would be great if any of the supposedly hundreds of letters written TO him that the police found came up one day. Karl Evanzz supposedly got the Detroit field office FBI file on the NOI which supposedly had details that no other document contained, including info from the local police's files after they arrested original members. However, evanzz gave his papers to Howard Univ, and when I made a request for the Detroit file, they couldn't find it in the collection.

B) documents related to other early black groups such as Satti Majid's Moslem Welfare Society and Abdul Hamid Suleiman's Canaanite Temple (and of course Noble Drew Ali's 1913 Moorish Temple). Of particular value would be the State Department records of the 1922 Shriner push to have Suleiman investigated. Unfortunately, the State Dept says they can't find it.

Other than that, I am proud to say that I recently discovered a document, tucked away in an extremely rare microfilm collection, that no one ever had any idea existed before: A letter used for organizing the very first Sufi group in the US (pre-Inayat Khan)--and perhaps the first Sufi group for ANY modern white europeans/americans

Letters are excellent sources for the study of late antiquity and the massive Register of Pope Gregory the Great stands out even today due to the range of topics covered. He corresponded with emperors, kings and heretics from across the Christian world, making it an outstanding source for the end of the sixth century. Unfortunately, his successors' letter-collections were not preserved in a similar way and we have to make do with only a small number of letters preserved principally in the records of church councils (such as from the Lateran Synod of 649, the Ecumenical Council of 680 and the gazillion Councils of Toledo in Spain), so we get the impression that popes after Gregory were seemingly only interested in doctrinal issues, not political and administrative matters, which was obviously not the case. What is particularly fascinating is the fact that the seventh century was an extended crisis for the Byzantine Empire and that we have no contemporary Greek histories or chronicles to tell us what happened, so we have to reconstruct events from religious and non-Greek sources. From the sources we have, the papacy emerges as a shadowy power acting behind the scenes of major revolts and religious controversies, which I think is a very dramatic demonstration of how western bishops were still intimately involved in Byzantine affairs.

So what do we know? Pope Honorius I in the 630s had agreed to the monothelete doctrine proposed by the Byzantine emperor Heraclius and Patriarch Sergius of Constantinople, an act that must have angered many Chalcedonians in the west, yet from the sources we only hear of eastern dissidents. The papacy then did a volte-face after Honorius' death and condemned monotheletism openly from 640 onwards, which in my opinion directly caused a revolt by the Byzantine governor of North Africa in 646 - what wouldn't I give to read the letters exchanged between Rome and Africa at this time! Pope Theodore I also began to prepare for a synod to be held in Rome to condemn monotheletism, which was again a giant slap to the face of Constantinople. From the list of attendees, it is clear that it was an overwhelmingly Italian synod, yet records also indicate that there was support from Francia and Visigothic Spain, so why were there no attendees from the west?

Theodore died before the council was held, so Martin I became the pope chairing the treasonous proceedings. A Byzantine exarch was sent to arrest the pope in the synod's aftermath, but for some reason the exarch turned against the emperor and began a civil war in Italy on the pope's side in 652! Again, we only have a few hints of what happened in this revolt; we have a few letters from Martin urging bishops across Christendom to side with him, so I do wonder to what extent did he urge for secular officials to join his side too. A bit later there were purges within the Byzantine aristocracy that can plausibly be tied to this too, so my pet theory is that the anti-monotheletes' influence was widespread across the empire and took years to be completely wiped out.

The exarch died soon after and Martin was arrested (for realsies) in 653. The next two popes were pro-imperial candidates imposed on Rome and they swiftly reconciled with the heretical emperor Constans II. This period is perhaps even less known, since both the papacy and the emperor after 680 (when monotheletism was condemned as a heresy) had no interest in preserving what happened in those years. Still, the hints we have are absolutely fascinating, since it looks like a North African monk served as an imperial ambassador to Francia and was seemingly involved in a plot to bring down Burgundy, whilst another monk, Theodore of Tarsus (incidentally one of the dissidents in 649), was appointed by the pro-imperial Pope Vitalian to the archbishopric of Canterbury. Was Constans II trying to extend imperial influence to Francia and beyond through the papacy? Was he trying to heal the wounds made by rebellious popes from the 650s? All these questions would be answered if only more papal letters survived...

Although a lot of the data has been published so I can't be too upset, the sheer pointlessness of the destruction of the Nemi ships still gets to me. It is also a little frustrating that there is no real certainty over who was to blame, although to be frank the Allies' explanation always struck me as a little mustache-twirly.

For many documents in my field, it was not that they have been lost, but they were never recovered in the first place. Many African-American newspapers were never saved beyond a few years past their original publication date and thus major sources of ethnic communities have been lost. In addition to seemingly simple sources of history such as newspapers, the whole of African-American history is being tainted by a lack of primary sources, oral interviews are hard to come by (in part due to the traumatic events associated with their communities) and the problems with literacy that were endemic early on leave few letters and diaries in some areas. One thing that actually comes to mind where an important series of artifacts being saved was the donation of the Richard Samuel Roberts photographic plates to the University of South Carolina. Roberts was an African-American photographer in the 1920's and 30's specializing in photographing African-American people and society. After his death, all the remaining glass plates were placed under the house for saving. It was not until the late 1970's that researchers were able to locate and preserve the plates, as well as reprint them in their entirety, has conditions been slightly different, or it had taken longer to recover, these important images would've been lost.

The most important letter signed by Soekarno, dubbed Supersemar (Surat Peritah Sebelas Maret) or the March 11^th Command Letter that gave birth to New Order and ended the era of Soekarno is... not really lost, but there are three different versions that are being kept in National Archive right now, and are believe to be fake.

First version was issued by the Secretary with Garuda letterhead, was short and to the point.

The second was issued by the Army with Garuda letterhead, stating Soeharto as Revolution General and added one more command while embellishing the first command.

The third doesn't have any letterhead whatsoever or any information who issued it, and Soekarno's sign is also slightly different than the other two.

President's formal letterhead should be stars with cotton and rice-paddy and not Garuda.

The letter supposedly gave all the rights for Soeharto, our second president, to take any means necessary to quell the dire situations pasca Indonesian Communist Party riot and subsequent purge.

Soeharto then used this letter as justification for massacring Communist Party members and every person who had ever donated money to the party (mostly Chinese - Indonesian), executed fifteen Soekarno's loyalist generals, and suppressed media's news report at the time.

A year later, Soeharto became President without election.

Many silent films from the silent film era are (unfortunately) deemed lost. It's really sad to think that there are thousands of hours of film that no longer exist. There may have been movie stars that we have very little or no record of studying.

In October of 1833, William Henry Fox Talbot was visiting Lake Como, Italy and attempting to make sketches using a Camera Lucida. Unsuccessful, he began to think of another way to capture the image. He wrote a note to remind himself of potential experimentation on the idea of capturing an image. This essentially marked the first time William Henry Fox Talbot, the inventor of the Calotype, thought about any sort of photographic process. Since then, the note has been lost, but Talbot transcribed it into one of his many journals a couple months after writing the original note. The journal reads:

Nitrate of Silver. Wash a sheet of paper with it. Place a leaf of fennel or other of complicated form upon it. Press it down with a pane of glass - when blackened with the sunshine place it in something that will alter its property of blackening - qu. Prussiate of potash? Sulp. Acid. Mur Soda. Carb. Soda. Instead of the leaf try several bits of coloured glass - thus a silhouette might be taken, especially in a dark room.

These early ideas for experimentation are what led Talbot to create one of the first photographic processes in our history. I, personally, just think it would be interesting to see and preserve the note. Mostly because it could be labeled as a starting point for the experimentation of the Calotype.

Source: Roger Watson, Helen Rappaport. Capturing the Light. New York: St Martins Press. 91-94

Of the lost works of Archimedes of Syracuse that we know about, the most intriguing to me is On Sphere-Making, mentioned in Book VIII of the Collection by Pappus of Alexandria (see Chapter 3 in S. Cuomo, Pappus of Alexandria and the Mathematics of Late Antiquity). This apparently contains a description of a miniature planetarium Archimedes built, "a sphere constructed so as to imitate the motions of the sun, the moon, and the five planets in the heavens." (Heath, The Works of Archimedes, p. xxi).

Here is an excerpt from a description, from Cicero's De Re Publica, of a device which he says was Archimedes' "sphere" (source and commentary here):

But when Gallus began to give a very learned explanation of the device, I concluded that the famous Sicilian had been endowed with greater genius than one would imagine it possible for a human being to possess. [...] this newer kind of globe, he said, on which were delineated the motions of the sun and moon and of those five stars which are called wanderers [the five visible planets], or, as we might say, rovers, contained more than could be shown on the solid globe, and the invention of Archimedes deserved special admiration because he had thought out a way to represent accurately by a single device for turning the globe those various and divergent movements with their different rates of speed.

It's likely that the contents would bring us some clarity on the mysteries surrounding the Antikythera mechanism.

Speaking of Archimedes and lost works, Johan Heiberg's discovery of the Archimedes palimpsest is an extraordinary lost-and-found story. The codex contains several works by Archimedes, some of which were previously thought to be lost, hidden under a 13-th century Christian religious text.