A grasp of chronology, simple as it may seem, is a fundamental skill of any historian. By "chronology," we mean what happened, in which order.

Chronology is important because the exact order in which events occur helps us understand the cause and the effect of those events, and thereby allow us to step back and view the "big picture" of history - how and why events unfold in the way they do, and how they are related.

In order to establish the exact order in which events unfold, consider preparing detailed timelines of the period you are studying. Such timelines will ensure that you always maintain an overview of the sequence of events at stake, and that you do not confuse cause and effect.

In the section on narrative history we provide a timeline of Hitler's foreign policy prior to World War II; in this section, we offer another timeline, below, on U.S.-Japanese relations prior to the United States' entry into the war. Based on the exact sequence of events, we will draw your attention to some interesting aspects of America's entry into the war, which those without a firm grasp of the chronology risk missing.

The following timeline is based on the information provided in the World War II-chapter of a standard college-level textbook of American history:

James L. Roark, et al. The American Promise: A History of the United States, v. 2: From 1865, 3rd edition. New York: Bedford St. Martin's, 2005. 916-918:

Significant moments in the evolution of U.S.-Japanese Relations prior to Pearl Harbor:

  • 1931 Japan attacks Manchuria.
  • 1933 FDR elected president of the United States.
  • 1937 October 5, FDR holds the "quarantine" speech in Chicago in an effort to position the U.S. to take a larger role in global affairs (see Response Papers; the speech is reproduced in the Archives).
  • 1937 December 13, Japanese troops take the city of Nanking, China. During the ensuing six week-occupation (a period referred to as "the Rape of Nanking") they commit widespread atrocities (on which, see Book Reviews, Historiographic Essays, and Evaluating Contradictory Data and Claims).
  • 1939 September 1, Germany attacks Poland; England and France declare war against Germany on September 3: World War II begins.
  • 1940 September 27, Japan signs Tripartite Pact with Germany and Italy, forming a three-way alliance.
  • 1941 Spring, U.S. cryptographers break Japan's secret transmission codes; the U.S. has the ability to eavesdrop on Japanese communications.
  • 1941 July, FDR announces a trade embargo that denies Japan access to oil and scrap iron.
  • 1941 August, FDR and British Prime Minister Winston Churchill meet in a ship off the Atlantic coast of Canada, pledging their nations to freedom of the seas, free trade, and the principle of national self-determination (the "Atlantic Charter"); Roosevelt promises Churchill that he will "be on the lookout for some incident that might trigger public support for full-scale American entry into the war against Germany" (Roark 916).
  • 1941 October, Japanese militarists seize Japan's government and persuade Emperor Hirohito that the time is right for a surprise attack on U.S. Pacific naval bases.
  • 1941 November - early December; U.S. intelligence intercepts numerous Japanese messages indicating "that an attack on U.S. forces was imminent somewhere in the Pacific" (Roark 917).
  • 1941 November 26, FDR orders aircraft carriers out of Pearl Harbor.
  • 1941 December 7, Japan attacks Pearl Harbor.
  • 1941 December 8, the United States declares war on Japan.

The events listed above are all well-established, but are usually presented non-chronologically. In a series of paragraphs devoted to the deteriorating American-Japanese relations, textbooks generally mention, in no particular order, that the U.S. had broken Japan's codes, that FDR imposed a trade embargo on Japan, that the U.S. intercepted Japanese messages warning of an attack on U.S. Pacific bases, that FDR ordered aircraft carriers removed from Pearl Harbor, that Japan attacked Pearl Harbor, and that FDR, declaring December 7 "a date which will live in infamy," was finally able to rally the previously isolationist nation to action after Japan's "surprise attack." (This, incidentally, is the way Roark's American Promise presents the information, on pp. 916 918, although not quite this chronologically.)

Notice how the exact order of events, as listed above, raises interesting questions. Just how much of a "surprise attack" was Pearl Harbor, do you think? What factors in the timeline above suggest that the U.S. might have had prior knowledge? Why would the U.S. have allowed the attack to occur, if (as some argue) it knew the attack was imminent? Why not attack Japan preemptively? Why remove American aircraft carriers from Pearl Harbor prior to the attack? What significance do you ascribe to FDR's purported comment to Churchill that he would seek out "some incident that might trigger public support for full-scale American entry into the war against Germany" (916)? How did the Japanese attack on Pearl Harbor contribute to this effort?

It remains unknown whether or not FDR knew about the impending attack, and whether he might even have deliberately provoked it, beginning with the trade embargo. Nevertheless, historians have been mulling over issues such as those listed above for decades. Once you have the exact chronology of events down, you too can begin asking questions and proposing answers on this, and any interesting topic in history.