bigpigeon.us webpage World Wars, updated by RAC 4 Feb 2020.
The World Wars, along with the related WW II Dead, WW II - Japan and WW II - Germany webareas, currently summarize American involvement in WW II with a focus on the Pottawattamie County area. 
Links to Big Pigeon's The World Wars subpages:
World War II Overview
I treat WW II as two wars in two different geographic areas:
  • Our War with Japan, with our primary allies being The Republic of China and the British Empire and Commonwealths. This war began in December 1941 with Japanese attacks on Pearl Harbor and elsewhere in east Asia and the Pacific. Combat ended in August 1945 after the US use of two atomic bombs on the Japanese homeland. The Japanese war was fought throughout much of eastern and southeastern Asia and the western and central Pacific. 
  • Our War with Germany, with primary allies being the British Empire and Commonwealths and the Soviet Union. Germany began this war by invading Poland in September 1939 and extended it by invading the Soviet Union in June 1941. United States active involvement began in December 1941 and ended in May 1945 with the collapse of the German government and German military resistance. The German component of World War II was fought throughout most of Europe and North Africa.
Planned Division of Eurasia
Japanese Proposed Division of Eurasia, 15 Dec 1941
 As the above map shows, the War with Japan and the War with Germany were quite separate geographically. The four thick arrows show planned offensives that would have brought the Axis forces together, but fortunately never happened.

The red and organge areas represent the Axis powers, their allies, and the territory they occupied as of September 1942.  
The United States was already drifting towards war with both Japan and Germany when the Japanese launched their fateful surprise attacks on December 7, 1941. (December 8  west of the International Date Line.)
  • Japan -  the United States had imposed economic sanctions attempting to curtail Japan's brutal aggression in China and expansionist tendencies in the southeast Asia area. 
  • Germany - the United States was taking increasingly bold actions in the North Atlantic to maintain the maritime supply line to England.
Some comments on my WW II webareas scope and perspective:
  • ​​The summaries in my WW II - Japan and WW II - Germany webareas focus on United States involvement in WW II. Even though only about 1% of those who died worldwide because of WW II were American, I emphasize the American experience.
  • Bloody as WW II was for the world at large, within the United States more (North and South combined) died in our Civil War than in WW II.
  • My goal - To memoriaize the men and women of the Pottawattamie County, Iowa area who served in World War II, and especially to remember those who did not survive.
  • Thus my World War II webareas contain about fifty webpages which summarize or outline a battle or campaign followed by a list of the Pottawattamie County area fallen during that event.
Notes:
  • Throughout this webarea, I use maps to support my text. You can usually enlarge a map or photo by clicking on it. 
WW II combat deaths, military deaths, and civilian deaths
We cannot hope to know the total worldwide deaths - military and civilian - caused by World War II. Reliable approximations are surprisingly hard to find. Figures offered by seemingly solid sources are often incorrect. As two examples:
  • The French Army Museum at Les Invalides in Paris has ignored my two request to include Hungarian deaths of around 300,000 military and 600,000 civilians in their display of World War II losses by country.  
  • For years, figures for total Allied deaths in Normandy on D-Day were grossly understated at 2,500. Recent research gives a confirmed figure of 4,400+, of whom about 2,500 were American.

The problem of unreliable data is compounded by slopping writing and the misuse of the word casualty. A casualty is either killed in action, captured, or wounded so seriously that he can no longer be an effective combatant. In most land combat, casualties far outnumber those killed.
  • As an example of sloppy writing, I quote from a current article on history.com: "German casualties on D-Day, meanwhile, have been estimated to be between 4,000 and 9,000 killed, wounded or missing. The Allies also captured some 200,000 German prisoners of war." The first figures are for June 6 only. The 200,000 captured figure is for the entire Normandy Campaign, which began on June 6. 

Somewhere between 400,000 and 500,000 Americans died because of World War II. A figure closer to 400,000 is generally seen. I believe it is too low, as it also excludes civilian Merchant Marine deaths (around 11,000) and those who died from service-related causes after being released from service.
Credits for The World Wars webpage
  • For my The World Wars webpage image, I intentionally chose a painting that represents a common feature of both WW I and WW II, the use of explosives - delivered primarily by artillery in WW I and by aircraft in WW II - to wreak physical destruction, often on civilian targets, on a scale impossible in earlier wars. The painting is by William F. Draper, an American combat artist.
  • The Planned Division of Eurasia map is courtesy of en.wikipedia.org.