Article: Attack on Pearl Harbor
Section: Aftermath

Question: When the did US declare war on Japan relative to Great Britain?

In the wake of the attack, 15 Medals of Honor, 51 Navy Crosses, 53 Silver Stars, four Navy and Marine Corps Medals, one Distinguished Flying Cross, four Distinguished Service Crosses, one Distinguished Service Medal, and three Bronze Star Medals were awarded to the American servicemen who distinguished themselves in combat at Pearl Harbor.
Additionally, a special military award, the Pearl Harbor Commemorative Medal, was later authorized for all military veterans of the attack.
The day after the attack, Roosevelt delivered his famous Infamy Speech to a Joint Session of Congress, calling for a formal declaration of war on the Empire of Japan.
Congress obliged his request less than an hour later.
On December 11 Germany and Italy, honoring their commitments under the Tripartite Pact, declared war on the United States.
The Tripartite Pact was an earlier agreement between Germany, Italy and Japan which had the principal objective of limiting U.S. intervention in any conflicts involving the three nations.
The United States Congress issued a declaration of war against Germany and Italy later that same day.
Britain actually declared war on Japan nine hours before the US did, partially due to Japanese attacks on Malaya, Singapore and Hong Kong, and partially due to Winston Churchill's promise to declare war "within the hour" of a Japanese attack on the United States.
The attack was an initial shock to all the Allies in the Pacific Theater.
Further losses compounded the alarming setback.
Japan attacked the Philippines hours later (because of the time difference, it was December 8 in the Philippines).
Only three days after the attack on Pearl Harbor, the "Prince of Wales" and "Repulse" were sunk off the coast of Malaya, causing British Prime Minister Winston Churchill later to recollect "In all the war I never received a more direct shock.
As I turned and twisted in bed the full horror of the news sank in upon me.
There were no British or American capital ships in the Indian Ocean or the Pacific except the American survivors of Pearl Harbor who were hastening back to California.
Over this vast expanse of waters Japan was supreme and we everywhere were weak and naked".
Throughout the war, Pearl Harbor was frequently used in American propaganda.
One further consequence of the attacks on Pearl Harbor and its aftermath (notably the Niihau Incident) was that Japanese American residents and citizens were relocated to nearby Japanese-American internment camps.
Within hours of the attack, hundreds of Japanese American leaders were rounded up and brought to high-security camps such as Sand Island at the mouth of Honolulu harbor and Kilauea Military Camp on the island of Hawaii.
Later, over 110,000 Japanese Americans, including United States citizens, were removed from their homes and transferred to internment camps in California, Idaho, Utah, Arizona, Wyoming, Colorado, and Arkansas.
The attacks also had international consequences.
The Canadian province of British Columbia, being situated on the Pacific coast, had long had a large population of Japanese immigrants.
Pre-war tensions were exacerbated by the Pearl Harbor attack, leading to a reaction from the Government of Canada.
On February 24, 1942, Order-in-Council P.C.
no.
1486 was passed under the War Measures Act allowing for the forced removal of any and all Canadians of Japanese descent from British Columbia, as well as the prohibiting from them returning to the province.
The Japanese were given a choice: either be moved into internment camps or be deported back to Japan.