March 1970: Four Sources, One Display Panel
At a high school in Battambang, the Grade 12 history club must mount a 300-word display on the events of March 1970 in Phnom Penh. The club has four items and two weeks. Item A is a 2008 audio interview with a former soldier who says the National Assembly vote came “right after the prince flew to Moscow” and gives 18 March. Item B is a 1995 typed memoir by a retired teacher who writes that “armed men moved into the city on 17 March.” Item C is a 2019 Facebook post by the teacher’s nephew, retelling family stories and attaching a photograph captioned “demonstrators, 1970”; the picture has no provenance. Item D is a photocopy of a 1971 magazine page that reports the vote, but its masthead and date line are cut off. The faculty adviser insists that every claim on the panel be sourced and that the panel not pretend to certainty where the evidence is thin.
1. Rank items A–D by their value as evidence for fixing the date of the National Assembly vote, and justify each ranking.
Read the worked answer
Ranking: D (conditional), A, B, C.
- D is closest in time (1971) and is a published source, so it was edited and dated at publication. But the missing masthead and date line mean the club cannot authenticate the page; as it stands it is an orphan fragment. Its value is high only if the club can locate the full issue or a library copy.
- A is an eyewitness account, but recorded 38 years later. Memory for a sequence (“after the prince flew to Moscow”) is usually stronger than memory for a calendar date, so A is better for sequence than for the exact day.
- B is also eyewitness testimony, but 25 years later and in a typed memoir that may have been revised; its 17 March date conflicts with A.
- C is third-hand, undated, and the photograph has no provenance. It is evidence of family memory, not of the event.
The reasoning is: authenticate first, then prefer independent over derivative sources, and prefer near-contemporary records for dates.
2. Two dates appear, 17 and 18 March. Explain how a historian should resolve the conflict and what could explain the discrepancy.
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Do not average the dates or choose the more vivid account. First ask what each date is a date of: the Assembly vote, troop movements, or the mid-March anti-Vietnamese demonstrations in Phnom Penh. A witness can merge a demonstration he saw with a vote he heard about, producing a one-day error.
Next, seek independent corroboration. If D, once authenticated, reports the vote, it fixes the event date more securely than either memory. If D confirms 18 March, then 17 March may refer to troops moving into the city the night before, or may simply be a memory error.
The panel can then say: “The National Assembly vote took place on 18 March 1970; some accounts place armed men in the city the previous day.” That wording is honest about the uncertainty and still communicates the sequence. The error to avoid is presenting a single eyewitness date as settled fact.
3. Write a caption for the photograph and a one-sentence caution line that would satisfy the adviser.
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Caption: “Unidentified demonstrators in Phnom Penh, March 1970. Photographer, exact date and original publication unknown; copy from a family collection.”
Caution line: “This image is used as an illustration of the period, not as evidence of the date, size or political character of the demonstration.”
Reasoning: a caption should separate what is known (the subject matter, the city, the approximate period), what is inferred (the month), and what is unknown (photographer, date, provenance). The caution line does real work: it prevents the photograph from being used to prove a claim it cannot support, and it tells the reader that the club knows the difference between illustration and evidence. That is exactly the standard the adviser set.