December 7, 1941 (Sunday)

• The Japanese surprise attack on Pearl Harbor began at 7:55 a.m. Hawaiian Time. 21 American ships and over 300 aircraft were sunk, destroyed or damaged, and 2,403 Americans were killed. Japan lost 29 planes in return.

• Japan declared war on the United States, Great Britain, Australia, Canada, New Zealand and South Africa.

• Winston Churchill was dining at Chequers, the country house of the Prime Minister of the United Kingdom, with the American diplomats John Gilbert Winant and W. Averell Harriman when the news of the Pearl Harbor attack arrived. Churchill realized that the United States would now enter the war and that Britain would no longer have to fight alone. He later wrote of that night, "Being saturated and satiated with emotion and sensation, I went to bed and slept the sleep of the saved and thankful."

• One hour after the Japanese attack, Australian Prime Minister John Curtin announced that "from one hour ago, Australia has been at war with the Japanese Empire." War would be formally declared two days later.

• Canada declared war on Finland, Hungary, Japan, and Romania.

• Panama declared war on Japan.

December 8, 1941 (Monday)

• New Zealand declared war on Japan at 11:00 a.m. New Zealand time.

• The Japanese carried out the Bombing of Singapore, killing 61.

• The Imperial Japanese Army occupies the Shanghai International Settlement. In the midst of this, HMS Peterel is sunk by the gunboat USS Wake, which has been hijacked by Japanese soldiers.

• President Roosevelt made the Infamy Speech (with its famous opening line "Yesterday, December 7, 1941, a date which will live in infamy,") to a Joint session of Congress. Within one hour the United States declared war on Japan. Lifelong pacifist Jeannette Rankin was the only member of Congress to vote against declaring war.

• The United Kingdom declared war on Japan.

• Costa Rica, the Dominican Republic, El Salvador, Haiti, Honduras, the Dutch government-in-exile and Nicaragua also declared war on Japan.

• The Japanese invasion of Thailand occurred. A ceasefire was reached in only a few hours; Thailand formed an alliance with Japan and declared war on the Allies.

• The Malayan Campaign, Philippines Campaign, Dutch East Indies campaign, Battle of Guam, Battle of Wake Island and Battle of Hong Kong began.

• Japanese troops invaded Batan Island.

December 9, 1941 (Tuesday)

• China formally declared war on Japan, Germany and Italy.

• Cuba and Guatemala declared war on Japan.

December 10, 1941 (Wednesday)

• The Japanese occupation of the Gilbert Islands began on Butaritari (Makin).

• Japanese forces invaded Vigan and Aparri.

• Los Angeles had its first blackout of the war.

December 11, 1941 (Thursday)

• Germany declared war on the United States. Hitler gave a speech to the Reichstag announcing the declaration of war.

• Italy declared war on the United States. "The powers of the steel pact, Fascist Italy and Nationalist Socialist Germany, ever closely linked, participate from today on the side of heroic Japan against the United States of America," Benito Mussolini declared in a statement.

• Germany, Italy and Japan signed a new pact barring any of them from making a separate peace with the United States or Great Britain.

• President Roosevelt sent a message to Congress asking for formal recognition of a state of war with Germany and Italy.

• The Polish and Dutch governments-in-exile declared war on Japan.

December 12: Romania and Bulgaria declared war on the United States and Britain; both countries responded in kind. Haiti, El Salvador and Panama declared war on Germany and Italy.

December 13: Hungary declared war on the United States. Great Britain, New Zealand and South Africa declared war on Bulgaria. Honduras declared war on Germany and Italy.

December 14: The Independent State of Croatia declared war on the United States and Britain.

December 16: The Czechoslovak government-in-exile declared war on all countries at war with the United States, Britain and the USSR.

December 17: Albania declared war on the United States.

December 19: Nicaragua declared war on Bulgaria, Hungary and Romania.

December 20: The Belgian government in exile declared war on Japan.

December 24: Haiti declared war on Bulgaria, Hungary and Romania.

December 7, 1941 (Sunday)

• The Japanese surprise attack on Pearl Harbor began at 7:55 a.m. Hawaiian Time. 21 American ships and over 300 aircraft were sunk, destroyed or damaged, and 2,403 Americans were killed. Japan lost 29 planes in return.

• Japan declared war on the United States, Great Britain, Australia, Canada, New Zealand and South Africa.

• Winston Churchill was dining at Chequers, the country house of the Prime Minister of the United Kingdom, with the American diplomats John Gilbert Winant and W. Averell Harriman when the news of the Pearl Harbor attack arrived. Churchill realized that the United States would now enter the war and that Britain would no longer have to fight alone. He later wrote of that night, "Being saturated and satiated with emotion and sensation, I went to bed and slept the sleep of the saved and thankful."

• One hour after the Japanese attack, Australian Prime Minister John Curtin announced that "from one hour ago, Australia has been at war with the Japanese Empire." War would be formally declared two days later.

• Canada declared war on Finland, Hungary, Japan, and Romania.

• Panama declared war on Japan.

December 8, 1941 (Monday)

• New Zealand declared war on Japan at 11:00 a.m. New Zealand time.

• The Japanese carried out the Bombing of Singapore, killing 61.

• The Imperial Japanese Army occupies the Shanghai International Settlement. In the midst of this, HMS Peterel is sunk by the gunboat USS Wake, which has been hijacked by Japanese soldiers.

• President Roosevelt made the Infamy Speech (with its famous opening line "Yesterday, December 7, 1941, a date which will live in infamy,") to a Joint session of Congress. Within one hour the United States declared war on Japan. Lifelong pacifist Jeannette Rankin was the only member of Congress to vote against declaring war.

• The United Kingdom declared war on Japan.

• Costa Rica, the Dominican Republic, El Salvador, Haiti, Honduras, the Dutch government-in-exile and Nicaragua also declared war on Japan.

• The Japanese invasion of Thailand occurred. A ceasefire was reached in only a few hours; Thailand formed an alliance with Japan and declared war on the Allies.

• The Malayan Campaign, Philippines Campaign, Dutch East Indies campaign, Battle of Guam, Battle of Wake Island and Battle of Hong Kong began.

• Japanese troops invaded Batan Island.

• China formally declared war on Japan, Germany and Italy.

• Cuba and Guatemala declared war on Japan.

December 10, 1941 (Wednesday)

• The Japanese occupation of the Gilbert Islands began on Butaritari (Makin).

• Japanese forces invaded Vigan and Aparri.

• Los Angeles had its first blackout of the war.

December 11, 1941 (Thursday)

• Germany declared war on the United States. Hitler gave a speech to the Reichstag announcing the declaration of war.

• Italy declared war on the United States. "The powers of the steel pact, Fascist Italy and Nationalist Socialist Germany, ever closely linked, participate from today on the side of heroic Japan against the United States of America," Benito Mussolini declared in a statement.

• Germany, Italy and Japan signed a new pact barring any of them from making a separate peace with the United States or Great Britain.

• President Roosevelt sent a message to Congress asking for formal recognition of a state of war with Germany and Italy.

• The Polish and Dutch governments-in-exile declared war on Japan.

December 12: Romania and Bulgaria declared war on the United States and Britain; both countries responded in kind. Haiti, El Salvador and Panama declared war on Germany and Italy.

December 13: Hungary declared war on the United States. Great Britain, New Zealand and South Africa declared war on Bulgaria. Honduras declared war on Germany and Italy.

December 14: The Independent State of Croatia declared war on the United States and Britain.

December 16: The Czechoslovak government-in-exile declared war on all countries at war with the United States, Britain and the USSR.

December 17: Albania declared war on the United States.

December 19: Nicaragua declared war on Bulgaria, Hungary and Romania.

December 20: The Belgian government in exile declared war on Japan.

December 24: Haiti declared war on Bulgaria, Hungary and Romania.