What did Doolittle's raid on Tokyo accomplish?

Answer 1

The raid itself caused very little damage, and resulted in the loss of all planes involved, and the capture of many of the crews.

However, it was a rousing success, nonetheless, for a variety of reasons:

1. For the American Public, it provided a huge morale boost in the dark days of early 1942, when very little was going the US's way in the war in the Pacific. It showed that the US was still able to "take the fight to the enemy."
2. It forced a significant re-alignment of Japanese naval and aviation forces, as, for domestic political reasons, having the Japanese homeland attacked (even if it was insignificant) was completely unacceptable. Thus, critical war resources were re-purposed for no good use other than to solve a political issue.