1941

December 7, 1941 – Japanese bomb Pearl Harbor, Hawaii; also attack the Philippines, Wake Island, Guam, Malaya, Thailand, Shanghai and Midway.
December 8, 1941 – U.S. and Britain declare war on Japan. Japanese land near Singapore and enter Thailand.
December 9, 1941 – China declares war on Japan.
December 10, 1941 – Japanese invade the Philippines and also seize Guam.
December 11, 1941 – Japanese invade Burma.
December 15, 1941 – First Japanese merchant ship sunk by a U.S. submarine. 
December 16, 1941 – Japanese invade British Borneo.
December 18, 1941 – Japanese invade Hong Kong.
December 22, 1941 – Japanese invade Luzon in the Philippines.
December 23, 1941 – General Douglas MacArthur begins a withdrawal from Manila to Bataan; Japanese take Wake Island.
December 25, 1941 – British surrender at Hong Kong.
December 26, 1941 – Manila declared an open city.
December 27, 1941 – Japanese bomb Manila.

1942

Map of the Japanese Empire at its peak in 1942.

January 2, 1942 – Manila and U.S. Naval base at Cavite captured by the Japanese.
January 7, 1942 – Japanese attack Bataan in the Philippines.
January 11, 1942 – Japanese invade Dutch East Indies and Dutch Borneo.
January 16, 1942 – Japanese begin an advance into Burma.
January 18, 1942 – German-Japanese-Italian military agreement signed in Berlin.
January 19, 1942 – Japanese take North Borneo.
January 23, 1942 – Japanese take Rabaul on New Britain in the Solomon Islands and also invade Bougainville, the largest island.
January 27, 1942 – First Japanese warship sunk by a U.S. submarine.
January 30/31 – The British withdraw into Singapore. The siege of Singapore then begins.
February 1, 1942 – First U.S. aircraft carrier offensive of the war as YORKTOWN and ENTERPRISE conduct air raids on Japanese bases in the Gilbert and Marshall Islands.
February 2, 1942 – Japanese invade Java in the Dutch East Indies.
February 8/9 – Japanese invade Singapore.
February 14, 1942 – Japanese invade Sumatra in the Dutch East Indies.
February 15, 1942 – British surrender at Singapore.
February 19, 1942 – Largest Japanese air raid since Pearl Harbor occurs against Darwin, Australia; Japanese invade Bali.
February 20, 1942 – First U.S. fighter ace of the war, Lt. Edward O’Hare from the LEXINGTON in action off Rabaul.
February 22, 1942 – President Franklin D. Roosevelt orders General MacArthur out of the Philippines.
February 23, 1942 – First Japanese attack on the U.S. mainland as a submarine shells an oil refinery near Santa Barbara, California.
February 24, 1942 – ENTERPRISE attacks Japanese on Wake Island.
February 26, 1942 – First U.S. carrier, the LANGLEY, is sunk by Japanese bombers.
February 27- March 1 – Japanese naval victory in the Battle of the Java Sea as the largest U.S. warship in the Far East, the HOUSTON, is sunk.
March 4, 1942 – Two Japanese flying boats bomb Pearl Harbor; ENTERPRISE attacks Marcus Island, just 1000 miles from Japan.
March 7, 1942 – British evacuate Rangoon in Burma; Japanese invade Salamaua and Lae on New Guinea.
March 8, 1942 – The Dutch on Java surrender to Japanese.
March 11, 1942 – Gen. MacArthur leaves Corregidor and is flown to Australia. Gen. Jonathan Wainwright becomes the new U.S. commander.
March 18, 1942 – Gen. MacArthur appointed commander of the Southwest Pacific Theater by President Roosevelt.
March 18, 1942 – War Relocation Authority established in the U.S. which eventually will round up 120,000 Japanese-Americans and transport them to barb-wired relocation centers. Despite the internment, over 17,000 Japanese-Americans sign up and fight for the U.S. in World War II in Europe, including the 442nd Regimental Combat Team, the most decorated unit in U.S. history.
March 23, 1942 – Japanese invade the Andaman Islands in the Bay of Bengal.
March 24, 1942 – Admiral Chester Nimitz appointed as Commander in Chief of the U.S. Pacific theater.
April 3, 1942 – Japanese attack U.S. and Filipino troops at Bataan.
April 6, 1942 – First U.S. troops arrive in Australia.
April 9, 1942 – U.S. forces on Bataan surrender unconditionally to the Japanese.
April 10, 1942 – Bataan Death March begins as 76,000 Allied POWs including 12,000 Americans are forced to walk 60 miles under a blazing sun without food or water toward a new POW camp, resulting in over 5,000 American deaths.
April 18, 1942 – Surprise U.S. ‘Doolittle’ B-25 air raid from the HORNET against Tokyo boosts Allied morale.
April 29, 1942 – Japanese take central Burma.
May 1, 1942 – Japanese occupy Mandalay in Burma.
May 3, 1942 – Japanese take Tulagi in the Solomon Islands.
May 5, 1942 – Japanese prepare to invade Midway and the Aleutian Islands.
May 6, 1942 – Japanese take Corregidor as Gen. Wainwright unconditionally surrenders all U.S. And Filipino forces in the Philippines.
May 7-8, 1942 – Japan suffers its first defeat of the war during the Battle of the Coral Sea off New Guinea – the first time in history that two opposing carrier forces fought only using aircraft without the opposing ships ever sighting each other.
May 12, 1942 – The last U.S. Troops holding out in the Philippines surrender on Mindanao.
May 20, 1942 – Japanese complete the capture of Burma and reach India.
June 4-5, 1942 – Turning point in the war occurs with a decisive victory for the U.S. against Japan in the Battle of Midway as squadrons of U.S. torpedo planes and dive bombers from ENTERPRISE, HORNET, and YORKTOWN attack and destroy four Japanese carriers, a cruiser, and damage another cruiser and two destroyers. U.S. loses YORKTOWN.
June 7, 1942 – Japanese invade the Aleutian Islands.
June 9, 1942 – Japanese postpone further plans to take Midway.
July 21, 1942 – Japanese land troops near Gona on New Guinea.
August 7, 1942 – The first U.S. amphibious landing of the Pacific War occurs as 1st Marine Division invades Tulagi and Guadalcanal in the Solomon Islands.
August 8, 1942 – U.S. Marines take the unfinished airfield on Guadalcanal and name it Henderson Field after Maj. Lofton Henderson, a hero of Midway.
August 8/9 – A major U.S. naval disaster off Savo Island, north of Guadalcanal, as eight Japanese warships wage a night attack and sink three U.S. heavy cruisers, an Australian cruiser, and one U.S. destroyer, all in less than an hour. Another U.S. cruiser and two destroyers are damaged. Over 1,500 Allied crewmen are lost. 
August 17, 1942 – 122 U.S. Marine raiders, transported by submarine, attack Makin Atoll in the Gilbert Islands.
August 21, 1942 – U.S. Marines repulse first major Japanese ground attack on Guadalcanal.
August 24, 1942 – U.S. And Japanese carriers meet in the Battle of the Eastern Solomons resulting in a Japanese defeat.
August 29, 1942 – The Red Cross announces Japan refuses to allow safe passage of ships containing supplies for U.S. POWs.
August 30, 1942 – U.S. Troops invade Adak Island in the Aleutian Islands.
September 9/10 – A Japanese floatplane flies two missions dropping incendiary bombs on U.S. forests in the state of Oregon – the only bombing of the continental U.S. during the war. Newspapers in the U.S. voluntarily withhold this information.
September 12-14 – Battle of Bloody Ridge on Guadalcanal.
September 15, 1942 – A Japanese submarine torpedo attack near the Solomon Islands results in the sinking of the Carrier WASP, Destroyer O’BRIEN and damage to the Battleship NORTH CAROLINA.
September 27, 1942 – British offensive in Burma.
October 11/12 – U.S. cruisers and destroyers defeat a Japanese task force in the Battle of Cape Esperance off Guadalcanal.
October 13, 1942 – The first U.S. Army troops, the 164th Infantry Regiment, land on Guadalcanal.
October 14/15 – Japanese bombard Henderson Field at night from warships then send troops ashore onto Guadalcanal in the morning as U.S. planes attack.
October 15/17 – Japanese bombard Henderson Field at night again from warships.
October 18, 1942 – Vice Admiral William F. Halsey named as the new commander of the South Pacific Area, in charge of the Solomons-New Guinea campaign.
October 26, 1942 – Battle of Santa Cruz off Guadalcanal between U.S. And Japanese warships results in the loss of the Carrier HORNET.
November 14/15 – U.S. And Japanese warships clash again off Guadalcanal resulting in the sinking of the U.S. Cruiser JUNEAU and the deaths of the five Sullivan brothers.
November 23/24 – Japanese air raid on Darwin, Australia. 
November 30 – Battle of Tasafaronga off Guadalcanal.
December 2, 1942 – Enrico Fermi conducts the world’s first nuclear chain reaction test at the University of Chicago.
December 20-24 – Japanese air raids on Calcutta, India.
December 31, 1942 – Emperor Hirohito of Japan gives permission to his troops to withdraw from Guadalcanal after five months of bloody fighting against U.S. Forces

1943

January 2, 1943 – Allies take Buna in New Guinea.January 22, 1943 – Allies defeat Japanese at Sanananda on New Guinea.
February 1, 1943 – Japanese begin evacuation of Guadalcanal.
February 8, 1943 – British-Indian forces begin guerrilla operations against Japanese in Burma.
February 9, 1943 – Japanese resistance on Guadalcanal ends.
March 2-4 – U.S. victory over Japanese in the Battle of Bismarck Sea.
April 18, 1943 – U.S. code breakers pinpoint the location of Japanese Admiral Yamamoto flying in a Japanese bomber near Bougainville in the Solomon Islands. Eighteen P-38 fighters then locate and shoot down Yamamoto.
April 21, 1943 – President Roosevelt announces the Japanese have executed several airmen from the Doolittle Raid.
April 22, 1943 – Japan announces captured Allied pilots will be given “one way tickets to hell.”
May 10, 1943 – U.S. Troops invade Attu in the Aleutian Islands.
May 14, 1943 – A Japanese submarine sinks the Australian hospital ship CENTAUR resulting in 299 dead.
May 31, 1943 – Japanese end their occupation of the Aleutian Islands as the U.S. completes the capture of Attu.
June 1, 1943 – U.S. begins submarine warfare against Japanese shipping.
June 21, 1943 – Allies advance to New Georgia, Solomon Islands.
July 8, 1943 – B-24 Liberators flying from Midway bomb Japanese on Wake Island.
August 1/2 – A group of 15 U.S. PT-boats attempt to block Japanese convoys south of Kolombangra Island in the Solomon Islands. PT-109, commanded by Lt. John F. Kennedy, is rammed and sunk by the Japanese Cruiser AMAGIRI, killing two and badly injuring others. The crew survives as Kennedy aids one badly injured man by towing him to a nearby atoll. 
August 6/7, 1943 – Battle of Vella Gulf in the Solomon Islands.
August 25, 1943 – Allies complete the occupation of New Georgia.
September 4, 1943 – Allies recapture Lae-Salamaua, New Guinea.
October 7, 1943 – Japanese execute approximately 100 American POWs on Wake Island.
October 26, 1943 – Emperor Hirohito states his country’s situation is now “truly grave.”
November 1, 1943 – U.S. Marines invade Bougainville in the Solomon Islands.
November 2, 1943 – Battle of Empress Augusta Bay.
November 20, 1943 – U.S. Troops invade Makin and Tarawa in the Gilbert Islands.
November 23, 1943 – Japanese end resistance on Makin and Tarawa.
December 15, 1943 – U.S. Troops land on the Arawe Peninsula of New Britain in the Solomon Islands.
December 26, 1943 – Full Allied assault on New Britain as 1st Division Marines invade Cape Gloucester.

1944

January 9, 1944 – British and Indian troops recapture Maungdaw in Burma.
January 31, 1944 – U.S. Troops invade Kwajalein in the Marshall Islands.
February 1-7, 1944 – U.S. Troops capture Kwajalein and Majura Atolls in the Marshall Islands.
February 17/18 – U.S. Carrier-based planes destroy the Japanese naval base at Truk in the Caroline Islands.
February 20, 1944 – U.S. Carrier-based and land-based planes destroy the Japanese base at Rabaul.
February 23, 1944 – U.S. Carrier-based planes attack the Mariana Islands.
February 24, 1944 – Merrill’s Marauders begin a ground campaign in northern Burma.
March 5, 1944 – Gen. Wingate’s groups begin operations behind Japanese lines in Burma.
March 15, 1944 – Japanese begin offensive toward Imphal and Kohima.
April 17, 1944 – Japanese begin their last offensive in China, attacking U.S. air bases in eastern China.
April 22, 1944 – Allies invade Aitape and Hollandia in New Guinea.
May 27, 1944 – Allies invade Biak Island, New Guinea.
June 5, 1944 – The first mission by B-29 Superfortress bombers occurs as 77 planes bomb Japanese railway facilities at Bangkok, Thailand.
June 15, 1944 – U.S. Marines invade Saipan in the Mariana Islands.
June 15/16 – The first bombing raid on Japan since the Doolittle raid of April 1942, as 47 B-29s based in Bengel, India, target the steel works at Yawata. 
June 19, 1944 – The “Marianas Turkey Shoot” occurs as U.S. Carrier-based fighters shoot down 220 Japanese planes, while only 20 American planes are lost.
July 8, 1944 – Japanese withdraw from Imphal.
July 19, 1944 – U.S. Marines invade Guam in the Marianas.
July 24, 1944 – U.S. Marines invade Tinian.
July 27, 1944 – American troops complete the liberation of Guam.
August 3, 1944 – U.S. And Chinese troops take Myitkyina after a two month siege.
August 8, 1944 – American troops complete the capture of the Mariana Islands.
September 15, 1944 – U.S. Troops invade Morotai and the Paulaus.
October 11, 1944 – U.S. Air raids against Okinawa.
October 18, 1944 – Fourteen B-29s based on the Marianas attack the Japanese base at Truk.
October 20, 1944 – U.S. Sixth Army invades Leyte in the Philippines.
October 23-26 – Battle of Leyte Gulf results in a decisive U.S. Naval victory.
October 25, 1944 – The first suicide air (Kamikaze) attacks occur against U.S. warships in Leyte Gulf. By the end of the war, Japan will have sent an estimated 2,257 aircraft. “The only weapon I feared in the war,” Adm. Halsey will say later.
November 11, 1944 – Iwo Jima bombarded by the U.S. Navy.
November 24, 1944 – Twenty four B-29s bomb the Nakajima aircraft factory near Tokyo.
December 15, 1944 – U.S. Troops invade Mindoro in the Philippines.
December 17, 1944 – The U.S. Army Air Force begins preparations for dropping the Atomic Bomb by establishing the 509th Composite Group to operate the B-29s that will deliver the bomb.

1945

January 3, 1945 – Gen. MacArthur is placed in command of all U.S. ground forces and Adm. Nimitz in command of all naval forces in preparation for planned assaults against Iwo Jima, Okinawa and Japan itself.
January 4, 1945 – British occupy Akyab in Burma.
January 9, 1945 – U.S. Sixth Army invades Lingayen Gulf on Luzon in the Philippines.
January 11, 1945 – Air raid against Japanese bases in Indochina by U.S. Carrier-based planes.
January 28, 1945 – The Burma road is reopened.
February 3, 1945 – U.S. Sixth Army attacks Japanese in Manila.
February 16, 1945 – U.S. Troops recapture Bataan in the Philippines.
February 19, 1945 – U.S. Marines invade Iwo Jima.
March 1, 1945 – A U.S. submarine sinks a Japanese merchant ship loaded with supplies for Allied POWs, resulting in a court martial for the captain of the submarine, since the ship had been granted safe passage by the U.S. Government.
March 2, 1945 – U.S. airborne troops recapture Corregidor in the Philippines.
March 3, 1945 – U.S. And Filipino troops take Manila.
March 9/10 – Fifteen square miles of Tokyo erupts in flames after it is fire bombed by 279 B-29s.
March 10, 1945 – U.S. Eighth Army invades Zamboanga Peninsula on Mindanao in the Philippines.
March 20, 1945 – British troops liberate Mandalay, Burma.
March 27, 1945 – B-29s lay mines in Japan’s Shimonoseki Strait to interrupt shipping.
April 1, 1945 – The final amphibious landing of the war occurs as the U.S. Tenth Army invades Okinawa.
April 7, 1945 – B-29s fly their first fighter-escorted mission against Japan with P-51 Mustangs based on Iwo Jima; U.S. Carrier-based fighters sink the super battleship YAMATO and several escort vessels which planned to attack U.S. Forces at Okinawa.
April 12, 1945 – President Roosevelt dies, succeeded by Harry S. Truman.
May 8, 1945 – Victory in Europe Day.
May 20, 1945 – Japanese begin withdrawal from China.
May 25, 1945 – U.S. Joint Chiefs of Staff approve Operation Olympic, the invasion of Japan, scheduled for November 1.
June 9, 1945 – Japanese Premier Suzuki announces Japan will fight to the very end rather than accept unconditional surrender.
June 18, 1945 – Japanese resistance ends on Mindanao in the Philippines.
June 22, 1945 – Japanese resistance ends on Okinawa as the U.S. Tenth Army completes its capture.
June 28, 1945 – MacArthur’s headquarters announces the end of all Japanese resistance in the Philippines.
July 5, 1945 – Liberation of Philippines declared.
July 10, 1945 – 1,000 bomber raids against Japan begin.
July 14, 1945 – The first U.S. Naval bombardment of Japanese home islands.
July 16, 1945 – First Atomic Bomb is successfully tested in the U.S.
July 26, 1945 – Components of the Atomic Bomb “Little Boy” are unloaded at Tinian Island in the South Pacific.
July 29, 1945 – A Japanese submarine sinks the Cruiser INDIANAPOLIS resulting in the loss of 881 crewmen. The ship sinks before a radio message can be sent out leaving survivors adrift for two days.
August 6, 1945 – First Atomic Bomb dropped on Hiroshima from a B-29 flown by Col. Paul Tibbets.
August 8, 1945 – U.S.S.R. declares war on Japan then invades Manchuria.
August 9, 1945 – Second Atomic Bomb is dropped on Nagasaki from a B-29 flown by Maj. Charles Sweeney — Emperor Hirohito and Japanese Prime Minister Suzuki then decide to seek an immediate peace with the Allies.
August 14, 1945 – Japanese accept unconditional surrender; Gen. MacArthur is appointed to head the occupation forces in Japan.
August 16, 1945 – Gen. Wainwright, a POW since May 6, 1942, is released from a POW camp in Manchuria.
August 27, 1945 – B-29s drop supplies to Allied POWs in China.
August 29, 1945 – The Soviets shoot down a B-29 dropping supplies to POWs in Korea; U.S. Troops land near Tokyo to begin the occupation of Japan.
August 30, 1945 – The British reoccupy Hong Kong.
September 2, 1945 – Formal Japanese surrender ceremony on board the MISSOURI in Tokyo Bay as 1,000 carrier-based planes fly overhead; President Truman declares VJ Day.
September 3, 1945 – The Japanese commander in the Philippines, Gen. Yamashita, surrenders to Gen. Wainwright at Baguio.
September 4, 1945 – Japanese troops on Wake Island surrender.
September 5, 1945 – British land in Singapore.
September 8, 1945 – MacArthur enters Tokyo.
September 9, 1945 – Japanese in Korea surrender.
September 13, 1945 – Japanese in Burma surrender.
October 24, 1945 – United Nations is born.