The Japanese raid into the Indian Ocean is both a great what-if of World War II and an indication of the importance of Midway. The forces that could have pursued the advantage gained in the Indian Ocean moved instead to the Pacific, to lose four carriers, and many strategic options as well, in the critical June 1942 battle.
"Midway and the Indian Ocean,"
Naval War College Review: Vol. 62
, Article 9.
Available at: http://digital-commons.usnwc.edu/nwc-review/vol62/iss4/9