- German submarine U-38 sank Greek freighter Garoufalia off Norway; 4 were killed, 25 survived.
- Vidkun Quisling met with Erich Raeder in Germany.
- German freighter Rhein, already being monitored by American destroyers Simpson and MacLeish, was intercepted by Dutch destroyer Van Kinsbergen near the Florida Straits; her crew scuttled the ship to avoid capture.
- German submarine U-96 attacked Allied convoy HX-92 125 miles northwest of the Outer Hebrides, Scotland, United Kingdom, sinking British liner Rotorua at 1512 hours (21 were killed, including HX-92 commodore Rear Admiral Fitzgerald; 108 survived) and Norwegian ship Towa at 2242 hours (18 were killed, 19 survived).
- German submarine U-94 sank British ship Empire Statesman 225 miles west of Ireland at 1912 hours, killing the entire crew of 31.
- 278 German aircraft attacked Birmingham, England, United Kingdom, dropping 277 tons of high explosives and 685 incendiary bombs.
- Germany and Italy declare war on the United States. – On this day, Adolf Hitler declares war on the United States, bringing America, which had been neutral, into the European conflict. The bombing of Pearl Harbor surprised even Germany. Although Hitler had made an oral agreement with his Axis partner Japan that Germany would join a war against the United States, he was uncertain as to how the war would be engaged. Japan’s attack on Pearl Harbor answered that question. On December 8, Japanese Ambassador Oshima went to German Foreign Minister von Ribbentrop to nail the Germans down on a formal declaration of war against America. Von Ribbentrop stalled for time; he knew that Germany was under no obligation to do this under the terms of the Tripartite Pact, which promised help if Japan was attacked, but not if Japan was the aggressor. Von Ribbentrop feared that the addition of another antagonist, the United States, would overwhelm the German war effort. But Hitler thought otherwise. He was convinced that the United States would soon beat him to the punch and declare war on Germany. The U.S. Navy was already attacking German U-boats, and Hitler despised Roosevelt for his repeated verbal attacks against his Nazi ideology. He also believed that Japan was much stronger than it was, that once it had defeated the United States, it would turn and help Germany defeat Russia. So at 3:30 p.m. (Berlin time) on December 11, the German charge d’affaires in Washington handed American Secretary of State Cordell Hull a copy of the declaration of war. That very same day, Hitler addressed the Reichstag to defend the declaration. The failure of the New Deal, argued Hitler, was the real cause of the war, as President Roosevelt, supported by plutocrats and Jews, attempted to cover up for the collapse of his economic agenda. “First he incites war, then falsifies the causes, then odiously wraps himself in a cloak of Christian hypocrisy and slowly but surely leads mankind to war,” declared Hitler-and the Reichstag leaped to their feet in thunderous applause.
- In North Africa, the Italians reformed the line running south from the coast at Gazala with their armor on the right flank. Rommel’s Afrika Korps, reduced to just forty operational tanks after the Operation Crusader battles, protecting the open southern flank.
- North of Moscow, Russia, Soviet 16th Army captured Istra while Soviet 20th Army reached Solnechnogorsk. South of Moscow, Soviet troops captured Stalinogorsk.
- German submarine U-374 sank British anti-submarine trawler HMS Lady Shirley in the Strait of Gibraltar at 0421 hours, killing all 33 aboard. 21 minutes later, U-374 sank British patrol yacht HMS Rosabelle, which attempted to locate U-374; 30 were killed, 12 survived and rescued by patrol yacht HMS Sayonara.
- Adolf Hitler announced that since the start of the war against the Soviet Union, the German forces had captured 3,806,865 Soviet prisoners of war.
- Hans-Joachim Marseille shot down the British P-40 fighter piloted by Canadian Flight Sergeant M. A. Canty southeast of El Adem, Libya. It was his 32nd kill.
- The USAAF bombed Emden, Germany, while 18 RAF Mosquito aircraft attacked Duisburg, Germany.
- Adolf Hitler held a meeting with top German military commanders at the Adlerhorst headquarters in Wetterau, Germany, stressing the importance of the upcoming Ardennes Offensive.
- Kurt Fricke stepped down as the commanding officer of Naval Group Command South.
- It was forbidden to leave East Germany without permission. Violations were prosecuted with prison for up to three years.
- Heinrich Hoffmann passed away in München, Germany.
- West German Chancellor Willy Brandt and Czech Prime Minister Lubomir Strougal formally nullified the 1938 Munich pact when they signed a treaty sanctioning Hitler’s seizure of Czechoslovakia’s Sudetenland.