The writer of a May 11 letter about the U.S. intervention in World War II was correct in saying that the main factor was the Japanese attack on Pearl Harbor.
The war in Europe began on Sept. 1, 1939, when Germany invaded Poland. The next two years resulted in German domination of Europe, with the exception of Great Britain, which fought off invasion but was suffering severely. Also, beginning in the early 1930s, Japan had invaded Manchuria, China and French Indochina. However, isolationists prevailed and the U.S. did not intervene.
But on Dec. 7, 1941, Japan began attacks on the Philippines, Hong Kong, Singapore and Malaya and, in an attempt to cripple the U.S. fleet so it did not interfere in its plans for Southeast Asia, also bombed Pearl Harbor. The following day, President Franklin Roosevelt declared war on Japan. On Dec. 11, Germany and Italy declared war on the U.S.
It is interesting to speculate about what would have happened without Pearl Harbor, if isolationists had continued to prevail.
Adolf Hitler invaded Russia in June 1941. An estimated 80 percent of Germany's World War II casualties occurred on the eastern front. But even with a severely weakened German army the war could have gone on for many years. Instead, the Japanese attack on Pearl Harbor and the deaths of 2,400 Americans there led, in 1945, to the unconditional surrender of both aggressors.