Barron's has a very nice reproduction of one of Louise Yamada's charts. Go to Up and Down Wall Street for the verbiage.
...From there comes the hard part. Starting in November 1938, there was a 22% drop, qualifying for the 20% rule-of-thumb definition of a bear market; then a rally of 26%, fitting the definition of a bull market, into the fateful month of September 1939, the start of World War II.
Then came a series of bull and bear trades -- down 28%, up 23%, down 16%, up 13%, and the final decline into 1942 of 29%. After this nauseating roller-coaster ride, the market was down 41% from the 1938 highs (analogous to where we are now) to the 1942 lows....
That '42 low occurred on April 28 for the DJIA at 92.92. Since the previous December 7th, there had been nothing but bad news on the war fronts: Wake Island, Hong Kong, Manila, Kuala Lumpur and Singapore captured by the Japanese. The Prince of Wales sunk, the Normandie burns and turns turtle in New York. In March of '42 Roosevelt ordered all Japanese-Americans rounded up. On the East coast the German U-boat commanders were having what they called the (second) Happy Time, sinking some six hundred ships, virtually at will.
It was a very rough 20 weeks. I can't imagine having to go through something similar to see the bottom of the market.
On the other hand, I wonder what the equivalent of the Battle of Midway (June 4-7, '42) would be.