A complete investigation, start to finish

A worked investigation, from first idea to bibliography, on the removal of Japanese Americans in 1942: how the question developed, how seven real sources were chosen, and model text for all three sections.

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20 min readLast reviewed 16 Oct 2026

This page follows one historical investigation from start to finish: how the question took shape, how seven sources were chosen, and model text for each of the three sections, with commentary on why each part works. The topic is the decision of the United States government in early 1942 to remove all people of Japanese ancestry from the West Coast, most of whom were then held in camps for the rest of the Second World War. All seven sources are real and can be found in libraries or online.

A note on words. The US government spoke of "evacuation" and "relocation centers". Many historians and Japanese American organisations now prefer "forced removal" and "incarceration", because those held were not evacuated for their own safety, and because "internment" is properly the legal detention of enemy aliens, while about two-thirds of those held were US citizens. The model uses "removal" and "incarceration", and keeps the government's words when quoting it.

Step 1: from interest to question

The student's interest began with a family visit to the site of the Manzanar camp in California. The first topic, "Japanese American internment", covered four years and more than 120,000 people, so it could not be investigated in 2,200 words. The working question, "Why were Japanese Americans interned in 1942?", was narrower but open-ended: it invited a list of reasons.

Reading the 1982 report of the Commission on Wartime Relocation and Internment of Civilians showed the student where the disagreement lay. The government had justified the removal as a "military necessity" after the attack on Pearl Harbor of 7 December 1941; the commission concluded in 1982 that it was not. That gave the question a claim to test. Dates were set at December 1941 to March 1942, the months of the decision, and the question focused on removal from the West Coast, leaving the camps themselves to one side.

Stage	Wording	Problem or strength
Topic	Japanese American internment	A subject, not a question; four years, 120,000 people
Working question	Why were Japanese Americans interned in 1942?	Focused in time, but invites a list; "interned" is imprecise
Refined question	To what extent was military necessity the main reason for the removal of Japanese Americans from the West Coast in 1942?	Names one explanation to test against others (race prejudice, economic and political pressure, leadership); focused on one decision; uses cause and consequence and perspectives

Model Section 1 (about 380 words). Read it with the commentary that follows.

Show the model text

This investigation asks: To what extent was military necessity the main reason for the removal of Japanese Americans from the West Coast in 1942?

My interest began with a visit to the Manzanar National Historic Site in California, one of ten camps in which more than 120,000 people of Japanese ancestry were held during the Second World War. My first question, "Why were Japanese Americans interned in 1942?", was too open, and preliminary reading showed that "internment" was itself a contested word, since most of those held were American citizens rather than enemy aliens. I therefore focused on the decision that came first: the removal of all people of Japanese ancestry from the West Coast, authorised by President Roosevelt's Executive Order 9066 of 19 February 1942 and carried out in the following months.

The question became debatable when I read the report of the Commission on Wartime Relocation and Internment of Civilians (1982). The government and the army had justified removal as a military necessity after Pearl Harbor, arguing that Japanese Americans could not be screened for loyalty quickly enough to prevent sabotage. The commission rejected this, blaming race prejudice, war hysteria and a failure of political leadership. Rather than accept either verdict, I decided to test the claim of military necessity against the alternative explanations using evidence from the time.

The question uses the concept of cause and consequence. I distinguish the conditions that made removal possible (decades of anti-Japanese feeling on the West Coast), the short-term causes in December 1941 to February 1942 (fear after Pearl Harbor, pressure from politicians, newspapers and farming interests, and the advice of the army), and the decision itself. I judge "main reason" by asking whether the military case was necessary and sufficient for the decision, and whether those who made it believed it. The question also uses the concept of perspectives, because the same events were seen very differently by the army, by Japanese American leaders and by investigators forty years later.

The investigation covers December 1941 to March 1942 and the decision for mass removal, not conditions in the camps. It draws on government and military documents, statements by interested groups, a later official inquiry and a historian's study of the President's role.

Commentary. The question comes first. The development is told through specific steps, each with its reason (the site visit, the problem with "interned", the 1982 report). The debate is stated in a sentence on each side. The concept is not just named: the student explains how cause and consequence will be applied and sets two tests for "main reason". Scope and approach close the section without listing the sources, which belong in Section 2.

Step 2: choosing seven sources

The student shortlisted twelve sources and chose seven that between them covered the people who made the decision, the groups who pressed for or against it, and later investigators. The diagram of the seven sources shows them grouped by perspective.

The inquiry question in the centre, with seven sources around it. Top, inside government 1941–1943 (blue): Executive Order 9066, DeWitt's Final Report, the Munson report. Bottom left, interested groups at the time (orange): Anson quoted in the Saturday Evening Post, Masaoka's JACL statement. — The seven sources of the model investigation, grouped by perspective. Blue sources come from inside the government that made the decision; orange ones from groups outside it with a stake in the outcome; white ones look back after the event with access to records. Each group can answer a different part of the question.

	Source	Perspective	Why it was chosen
1	Franklin D. Roosevelt, Executive Order 9066, 19 February 1942	The President; the legal basis of the decision	States the official justification in the government's own words
2	J. L. DeWitt, Final Report: Japanese Evacuation from the West Coast, 1942 (Government Printing Office, 1943)	The army general who recommended and ran the removal	The fullest statement of the military case, including DeWitt's memorandum of 14 February 1942
3	C. B. Munson, report on Japanese Americans on the West Coast (1941), reprinted in J. Y. S. Wu and M. Song (eds), Asian American Studies: A Reader (2000)	An investigator sent by the government before Pearl Harbor	Shows what intelligence on loyalty was available before the decision
4	Austin E. Anson, quoted in Frank J. Taylor, "The People Nobody Wants", Saturday Evening Post, 9 May 1942	Californian farming interests who competed with Japanese American farmers	Tests the economic explanation
5	Mike Masaoka, statement for the Japanese American Citizens League to the House Select Committee Investigating National Defense Migration (Tolan Committee), San Francisco, February 1942	Japanese American leaders	The only source giving the view of those removed
6	Commission on Wartime Relocation and Internment of Civilians, Personal Justice Denied (1982)	A federal inquiry forty years later, with access to government records and hearing testimony from survivors	The official retrospective verdict that the student set out to test
7	Greg Robinson, By Order of the President: FDR and the Internment of Japanese Americans (Harvard University Press, 2001)	A historian focusing on the President	Tests the role of political leadership and Roosevelt's own views

Several sources were considered and left out. The Supreme Court's decision in Korematsu v. United States (1944) was rejected because it judged the order after the event; it explains how the courts saw military necessity, not why the decision was made. Books by David Lowman (2001) and Michelle Malkin (2004), which defend the decision on the basis of decoded Japanese diplomatic messages, were considered as the strongest statement of the military case. The student kept the army's own Final Report instead, because it shows what the decision-makers said at the time, but noted the argument in Section 3. A student who wanted to test military necessity harder could swap source 4 for one of these.

The key evidence

Three of the sources contain short passages that carry much of the argument. The first is the opening of the executive order itself.

Whereas the successful prosecution of the war requires every possible protection against espionage and against sabotage to national-defense material, national-defense premises, and national-defense utilities …

Franklin D. Roosevelt, Executive Order 9066, 19 February 1942 (National Archives). The order never mentions Japanese Americans: it authorises military commanders to exclude "any or all persons" from areas they designate. Its neutral security language is evidence of the justification the government wanted on record, but not of how the order would be used, which is why the army's report is needed beside it.

General John L. DeWitt, who commanded the Western Defense Command, set out his reasoning in a memorandum of 14 February 1942, reprinted in his Final Report.

The Japanese race is an enemy race and while many second and third generation Japanese born on United States soil, possessed of United States citizenship, have become "Americanized," the racial strains are undiluted.

J. L. DeWitt, memorandum of 14 February 1942, in Final Report: Japanese Evacuation from the West Coast, 1942, 1943. The same document argued that the absence of any sabotage so far was a sign that it was being planned. Written to justify the policy to the War Department and later to the public, it shows that the army's "military" case rested on assumptions about race, not on evidence of disloyalty, a point Justice Frank Murphy made in his dissent in the Korematsu case in 1944.

An economic motive was stated openly by the managing secretary of a Californian growers' association.

We're charged with wanting to get rid of the Japs for selfish reasons. We might as well be honest. We do. It's a question of whether the white man lives on the Pacific Coast or the brown men.

Austin E. Anson, Salinas Vegetable Grower-Shipper Association, quoted in Frank J. Taylor, "The People Nobody Wants", Saturday Evening Post, 9 May 1942. The racial slur is part of the historical evidence and is quoted as printed. Taylor reports that the association had sent Anson to Washington soon after Pearl Harbor to urge the removal of all Japanese from the area, so the lobbying came before the decision. But Anson was speaking after the order, to a national magazine, with an interest in presenting his group as influential, so the statement shows the motive of one interest group and its lobbying, not whether that lobbying shaped the decision in Washington.

Section 2: sources and perspectives

Model Section 2 (about 430 words). Read it with the commentary that follows.

Show the model text

I chose seven sources to represent three perspectives: those who made the decision, groups outside government with a stake in it, and investigators looking back.

The government's perspective comes from Executive Order 9066 and General DeWitt's Final Report. The order is the decision itself, so it is the most authoritative statement of the official justification, but its general language about "espionage" and "sabotage" hides how it was meant to be applied. DeWitt's report fills this gap: as the commander who recommended removal, he had every reason to present it as militarily necessary, and the report was compiled in 1943 to defend a policy already carried out. Its value for my question lies in exactly this, because it shows what the military case rested on. The Munson report offers a different view from inside government. Written before Pearl Harbor by an investigator sent to assess Japanese American loyalty, it had no stake in justifying removal and found the great majority loyal; its limitation is that it was written before the war began and could not take account of the fear that followed.

The second perspective is that of interested groups. Anson's statement, from a farming association that competed with Japanese American farmers, shows an economic motive for removal, although it was made after the order and may overstate his group's influence. Mike Masaoka's statement for the Japanese American Citizens League to a congressional committee in the days after the order gives the only voice of those removed: it insisted on their loyalty while promising to comply. Its purpose, to show cooperation at a moment of danger, limits it as evidence of what Japanese Americans privately thought, and the committee had no part in the decision.

The third perspective looks back. The 1982 Commission on Wartime Relocation and Internment of Civilians had access to government files and heard more than 750 witnesses; its conclusion that the decision was "not justified by military necessity" carries authority, but as a body set up after pressure from Japanese American campaigners for redress, its findings have been attacked by defenders of the policy as one-sided. Greg Robinson's study of Roosevelt (2001), based on presidential papers, is valuable for the role of leadership, but by focusing on one man it may give less weight to the pressure on him.

Missing from my sources are the views of Japanese Americans who opposed compliance, and of the officials in the Justice Department who argued against mass removal, whom I meet only through Robinson and the commission.

Commentary. Sources are grouped into three perspectives, not listed one by one. Each is judged for this question: DeWitt's purpose is turned into a reason why the report is useful, not just "biased". The selection is explained (Masaoka as the only voice of those removed), and the paragraph on silences names two missing perspectives. The 750 witnesses and the date of the commission are details the student found in the report itself.

Step 3: planning Section 3

Before drafting Section 3, the student wrote a one-sentence answer and mapped the evidence onto a grid of points and sources. The grid showed that every point drew on at least two sources, and that the counter-argument would need careful handling because the military case appears mainly in the army's own words.

Point in the argument	Sources used	What the evidence shows
1 The military case as presented at the time	1, 2, 6	A genuine fear after Pearl Harbor; but the order's security language and DeWitt's reasoning rest on race, not evidence
2 Evidence available against it	3, 5, 6	Intelligence before the war found Japanese Americans loyal; no sabotage occurred; Hawaii, much nearer the war, saw no mass removal
3 Pressure from outside the army	4, 6, 7	Economic rivals, West Coast politicians and newspapers demanded removal
4 Leadership and the decision in Washington	6, 7	Roosevelt accepted the War Department's case over the Justice Department's objections, without examining it
Counter-argument: the decision-makers believed it	2, 7 (and the MAGIC debate)	Belief in a threat can be a real cause even if the threat was not; weighed in the conclusion

One-sentence answer: Military necessity was the stated reason and a real fear, but it was not the main reason, because the military case was itself built on racial assumptions and accepted without scrutiny under political pressure.

Section 3: synthesis and evaluation

Model Section 3 (abbreviated: about 950 words; a full section would develop each point with more evidence and footnotes). Read it with the commentary that follows.

Show the model text

The removal of Japanese Americans from the West Coast was justified as a military necessity, and the fear of attack in early 1942 was real. Military necessity was nonetheless not the main reason for the decision. The military case was itself built on the assumption that ancestry decided loyalty, and it was accepted without scrutiny because political leaders shared that assumption and faced pressure from West Coast interests to act. Military necessity supplied the language of the decision more than its cause.

The military case rested on the fear that followed Pearl Harbor. In the weeks after 7 December 1941 Japan won a series of victories in the Pacific, and the commission later found that reports of espionage in Hawaii, published in January 1942, fed fears of sabotage on the coast. Executive Order 9066 presents removal in exactly these terms, as "protection against espionage and against sabotage". Yet the order is evidence of the justification, not of the reasoning behind it. That reasoning appears in DeWitt's memorandum of 14 February, which argued not that Japanese Americans had done anything but that "the racial strains are undiluted", and treated the absence of sabotage as proof that it was being planned. Because DeWitt wrote to justify a policy he had recommended, his report is strong evidence of what the army believed, and what it shows is that the military case depended on race. It was a necessity only if ancestry itself was a threat.

The evidence available to the government at the time points the same way. Munson, sent to assess loyalty before the war, found the great majority of Japanese Americans loyal, and his report reached senior officials before the decision. Masaoka's statement for the Japanese American Citizens League insisted on that loyalty, although its promise to comply shows how little room his community had to resist. The commission's finding that no Japanese American on the West Coast was shown to have committed sabotage or espionage is a retrospective judgement, but it is supported by DeWitt's own admission that none had occurred. Most telling is the comparison with Hawaii, much closer to the fighting, where people of Japanese ancestry made up about a third of the population and no mass removal took place, as the commission noted. If the danger had been military, the policy would have been strongest where the danger was greatest; it was not.

If the military case was weak, the question becomes why it was accepted, and part of the answer lies in pressure from outside the army. Anson's frank admission that his growers wanted rid of their Japanese American competitors shows that removal served economic interests, and the Saturday Evening Post reports that his association sent him to Washington to press for it soon after Pearl Harbor. As a statement published three months after the order, it shows the motive and the lobbying rather than proving their influence. The commission shows that the demand was much wider than one industry: in January and February 1942 West Coast newspapers, the national columnist Walter Lippmann and California's Attorney General, Earl Warren, all called for removal, and on 13 February the region's members of Congress formally recommended it. Farmers, politicians and journalists had different interests, so their agreement supports the commission's picture of a broad public clamour, although a body created after a campaign for redress had reason to stress the prejudice behind it. Pressure explains why removal was demanded; it cannot show why Washington agreed.

The decision itself was taken by the President. Robinson's study of Roosevelt, based on the presidential papers, shows that he had long regarded people of Japanese ancestry as unable to become fully American, and that in February 1942 he accepted the War Department's recommendation over the objections of his Attorney General, Francis Biddle, without asking for evidence. The commission reached a similar conclusion from the government's records, describing "a failure of political leadership". Robinson's focus on one man could exaggerate his role, but the two sources reach the same judgement from different evidence, which makes it more secure. Roosevelt did not need to be persuaded by the pressure from the coast, because he already shared the assumption on which the military case rested.

The strongest counter-argument is that the men who made the decision believed in the threat, and that a belief, even a mistaken one, can be a real cause. DeWitt's report expresses that belief, and later defenders of the decision, such as David Lowman and Michelle Malkin, have argued that decoded Japanese diplomatic messages of 1941 gave officials grounds for fear. This qualifies the argument: military fear was a necessary part of the decision, since without the war there would have been no removal. But it was not sufficient. The same fear did not produce mass removal of Japanese Americans in Hawaii, or of German and Italian Americans on the mainland, and the messages cited by Lowman and Malkin are not mentioned in DeWitt's own justification. What turned fear into removal was the assumption, stated by DeWitt and shared by the President, that ancestry decided loyalty.

Military necessity was therefore the stated reason for removal and a real anxiety in early 1942, but it was not the main reason. The military case collapses once its racial premise is removed, and it was accepted because political leaders shared that premise and faced pressure to act. This judgement rests mainly on government sources and a later inquiry; the voices of Japanese Americans appear only in a statement made under pressure, and a fuller investigation would test the conclusion against private letters and later oral testimony from those who were removed.

Commentary. The opening states a qualified judgement. Each paragraph begins with a point and combines at least two sources, often from different perspectives (DeWitt with the commission; Munson with Masaoka; Anson with the commission; Robinson with the commission). Evaluation is brief and placed where the evidence is used ("because DeWitt wrote to justify …"; "a statement published three months after the order"). The comparison with Hawaii and with German and Italian Americans is a test that turns facts into reasoning. The counter-argument is given its strongest form and answered with the distinction between necessary and sufficient causes. The conclusion answers in the question's own terms and states the limits of the evidence, returning to the silence noted in Section 2.

Step 4: references and bibliography

In the finished investigation each fact and quotation has a footnote. A sample of the footnotes for the model Section 3, in Chicago style:

J. L. DeWitt, Final Report: Japanese Evacuation from the West Coast, 1942 (Washington, DC: Government Printing Office, 1943), 34.
Commission on Wartime Relocation and Internment of Civilians, Personal Justice Denied (Washington, DC: Government Printing Office, 1982), [page].
Greg Robinson, By Order of the President: FDR and the Internment of Japanese Americans (Cambridge, MA: Harvard University Press, 2001), [page].

The bibliography lists exactly the seven sources, alphabetically by author or issuing body:

Commission on Wartime Relocation and Internment of Civilians. Personal Justice Denied. Washington, DC: Government Printing Office, 1982.
DeWitt, J. L. Final Report: Japanese Evacuation from the West Coast, 1942. Washington, DC: Government Printing Office, 1943.
Masaoka, Mike. Statement of the Japanese American Citizens League. In US House of Representatives, Select Committee Investigating National Defense Migration, Hearings, Part 29, San Francisco, February 1942.
Munson, C. B. "Japanese on the West Coast." In Asian American Studies: A Reader, edited by Jean Yu-wen Shen Wu and Min Song. New Brunswick, NJ: Rutgers University Press, 2000.
Robinson, Greg. By Order of the President: FDR and the Internment of Japanese Americans. Cambridge, MA: Harvard University Press, 2001.
Roosevelt, Franklin D. Executive Order 9066, 19 February 1942. National Archives. Accessed [date]. [URL].
Taylor, Frank J. "The People Nobody Wants." Saturday Evening Post, 9 May 1942.

The word count is stated at the start: Section 1 about 380 words, Section 2 about 430, and Section 3 about 1,350 in the full version, a total within 2,200 with footnotes and bibliography excluded.

Self-check

To do:
I can explain how a topic becomes a refined, debatable inquiry question, and record each step for Section 1.
To do:
I can choose up to seven sources for the range of perspectives they give, and explain why others were left out.
To do:
I can write a Section 2 that groups sources by perspective and judges each for my question.
To do:
I can plan Section 3 with a one-sentence answer and a grid of points and sources.
To do:
I can write argued paragraphs that combine and evaluate evidence from several sources.
To do:
I can answer the strongest counter-argument and write a conclusion that states the limits of my evidence.
To do:
I can footnote every fact and quotation to one of my sources and produce a correct bibliography.

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