"Remember the Texas," Or WWII Starts In The Atlantic
Here's another fun alternate timeline from the public section of the alternate history forum: "Remember the Texas! The United States in WWII." It diverges from real history in June 1941 when a German U-Boat captain mistakes the American battleship USS Texas for a British battleship and sinks it. Although the U.S. and Germany had an undeclared naval war going at this point, this represents a truly massive escalation. The United States declares war on Germany (even the isolationists are not going to tolerate this), despite the U.S. military being absolutely nowhere near ready.
(If you read An Army at Dawn, you can see how horrendously unprepared the U.S. was for Operation Torch, and that was much later against a much less motivated and less competent opponent.)
Highlights of the timeline include:
*Different British generals commanding in different theaters, which almost certainly means a more competent defense of Singapore when the Japanese come south. The author argues that Japan will attack Western colonies in Asia due to the same issues that drove their attack in our world, and with the Pacific undermanned they might have an easier time. In this world, that war begins in the Far East and there's no Pearl Harbor, so American society as a whole is not going to be as vengeful. Hopefully no Japanese Internment in this history--even J. Edgar Hoover thought that was a bad idea and he wasn't exactly a champion of civil liberties.
*A lot of experienced personnel are pulled out of the Philippines for the European war, which will make the islands' almost-inevitable fall much less severe for the U.S. in terms of personnel and equipment losses.
*Per the above, Douglas MacArthur commands U.S. forces in China. Given his blunders in the Philippines (this paper makes a strong case that the Japanese conquest was largely due to his mistakes), this is going to be another improvement on real history, although one wonders how an ego the size of MacArthur's would coexist with an ego the size of Chiang Kai-Shek's. Hopefully they can keep each other's yes-men away--as someone points out in the thread, MacArthur when he didn't have cronies telling him what he wanted to hear could come up with pretty clever stuff like the Inchon Landings.
*Operation Chariot, in real history the St. Nazaire Raid, gets beefed up with U.S. aircraft carriers and battleships into a much larger operation intended to hash the German fleet based in French ports and eliminate (or at least greatly diminish) the U-Boat threat. Most of the timeline so far consists of this world's Operation Chariot and discussion about how plausible this would be.