- Apr 1 . Japanese land on Buka and Santa Isabel, Solomons.
- Apr 4 . Hornet leaves San Francisco with Doolittle and 16 B-25's.
- Apr 5 . Jap fleet w/5 carriers attack Ceylon. Heavy cruisers HMS Cornwall and HMS Dorsetshire and two others sunk.
- Apr 5 . Imperial Japanese Navy battle plan for Midway accepted.
- Apr 6 . Rommel breaks through Commonwealth defense lines in Cyrenaica (Benghazi, Libya)
- Apr 6 . Japanese Malaya fleet sinks 23 merchantmen off Eastern India
- Apr 6 . Advance elements of the U.S. Army 41st Division reach Melbourne, Australia.
- Apr 7 . Japanese subs off western India sink 5 merchantmen this week.
- Apr 7 . Colorado only western state to agree to accept voluntary relocation of enemy aliens.
- Apr 7 . Relocation begins of Japanese from coastal defense zones.
- Apr 8 . Force from Rabaul lands in Western New Britain.
- Apr 8 . Enterprise departs Pearl to rendezvous with Hornet.
- Apr 8 . Submarine Seadragon (SS-194) delivers food to Corregidor; evacuates naval radio intelligence people.
- Apr 9 . US troops surrender on Bataan peninsula. Over 10% die in Death March
- Apr 9 . British warships sunk off Ceylon : Carrier HMS Hermes (CV.95), HMAS Vampire (D68), 2 others.
- Apr 10. Japanese start to take southern Philippines, Cebu.
- Apr 12. Victorious Japanese fleet starts its return to home waters having
lost no surface warships in war to date.
- Apr 13. Lexington (TF 11, RAdm Fitch) leaves Pearl to join Yorktown (TF 17, Fletcher) for raid on Rabaul.
- Apr 14. Adm Nimitz assigned to South Pacific. Sends Yorktown (CV-5, RAdm Fletcher) to Tongatabu,
south of Samoa, to replenish for anticipated defense of New Guinea and Solomon Islands at the end of the month.
- Apr 15. Rommel advance is overextended, stops at Egyptian boarder.
- Apr 16. Japanese land on Panay and Negros, Philippine Islands.
- Apr 17. Japanese army takes central Burma.
- Apr 17. Submarine Searaven (SS-196) begins rescue of stranded Australian servicemen from occupied Timor.
- Apr 18. Doolittle Raid on Tokyo with 16 Army B-25 bombers from Hornet, escorted by Enterprise.
- Apr 18. Lexington (CV-2, TF 11, RAdm Fitch), ferries USMC F2A Buffalos to Palmyra Island.
- Apr 19. Japanese land in Dutch New Guinea
- Apr 20. Lexington arrives S Pacific.
- Apr 20. Wasp (CV-7) ferries 47 RAF Spitfires to embattled British island of Malta in Mediterranean.
- Apr 21. Entire Japanese fleet searches for the Doolittle carriers.
- Apr 22. Lexington joins Yorktown at Tongutabu to prepare for expected battle in Coral Sea.
- Apr 23. Code breakers harvest intel from massive Japanese pursuit of Doolittle carriers.
- Apr 24. Japanese fleet elements start to return to refuel.
- Apr 25. Allied army forces begin retreat from Burma.
- Apr 25. Enterprise and Hornet arrive Pearl from Doolittle's Tokyo raid.
- Apr 26. Nimitz flies San Francisco to brief Adm King on South Pacific plan.
- Apr 27. Yorktown departs for Coral Sea.
- Apr 27. Seven battleships remain based on West Coast to conserve fuel.
- Apr 28. Coast watchers report Japanese flying-boat base established in
- Apr 28. VAdm Ghormley arrives from Europe to take South Pacific.
- Apr 29. Japanese land on Mindanao, southern Philippine Islands
- Apr 29. Japanese naval landing force occupies former RAAF seaplane base at Tulagi, Solomons.
- Apr 30. PBYs evacuate military and civilian personnel from Corregidor.
- Apr 30. Japanese cut China Road by capture of Lashio, Burma.
- Apr 30. Zuikaku and Shokaku sortie Truk to support Port Moresby invasion
leading to the Battle of Coral Sea.
- Apr 30. Enterprise and Hornet speed towards Coral Sea; too far to reach in time.
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