[5] At the time of the Japanese Attack on Pearl Harbor, the group began flying antisubmarine patrols and watching for signs of an invasion.

[5] In early May, the group deployed to Stockton Army Air Field, California, where half its crews stood alert during daylight hours.

[7][6] In June 1942, while in the United States for a conference with President Franklin D. Roosevelt, British Prime Minister Winston Churchill received word that the British Eighth Army had been defeated in a tank battle with Field Marshal Erwin Rommel's Afrika Korps near Tobruk, Libya, and was retreating back toward Alexandria, Egypt.

Churchill immediately made an urgent plea for military aid to help stop Rommel from over-running Egypt, the Suez Canal and the Arabian oil fields.

Ground personnel of all three groups and supporting units sailed from New York City on 16 July 1942 on the SS Pasteur, a fast French ocean liner that had been impressed by the British, for a month-long trip around South Africa and up the Red Sea to Suez, Egypt, arriving on 16 August 1942.

Losses, which included the group commander, Colonel Goodrich, caused the withdrawal of the unit from night operations until its planes could be modified with "finger exhausts".

The unit's first missions were flown to support forces opposing Rommel's final effort to break through to the Suez Canal at the Battle of Alam Halfa between 31 August and 4 September 1942.

The 12th Group and RAF forces attacked the airfields on 9 October, destroying ten enemy aircraft and damaging an additional 22.

There was little rest as ground crews rushed to refuel, reload bombs and ammunition, and patch flak holes, with operations peaking on 27 October.

By 4 November, Rommel began withdraw and main targets became columns of tanks, trucks and troops retreating to the west.

Just as the Mitchells were taking off, a dust storm hit the Landing Ground and only twelve planes were able to fly the mission, which had little effect on enemy forces.

[13] American forces under General Dwight D. Eisenhower landed in Algeria and Morocco, and were met by German divisions under Rommel's command.

After the fall of Tunis, the 12th was reunited at Hergla Airfield, Tunisia, and all of the personnel of its squadrons were together again for the first time since their advance parties moved out into the desert eight months earlier.

[14] The group's actions during the north African campaign earned it a Distinguished Unit Citation for its operations from primitive landing grounds under difficult weather and terrain conditions and, despite repeated enemy attacks on its advanced positions and limited resources, made a major contribution to the defeat of enemy forces in the Middle East.

[note 5] Later in August, the group moved to Gerbini Airfield on Sicily, from which it struck bridges, tunnels and other targets to support Operation Baytown, the invasion of southern Italy.

[17] The 12th Group moved to India to help the British Fourteenth Army repel a Japanese invasion from Burma toward Imphal, threatening the whole subcontinent and the Indian Ocean.

[note 7] The 12th flew its first mission as part of Tenth Air Force, bombing Japanese supply dumps at Mogaung, Burma, on 16 April 1944.

The lessened threat of flak in the new theater and added firepower of the updated Mitchells the group now flew resulted in a change of tactics.

[18] In April, Japanese forces that had broken out of the Burma mountains the previous month surrounded two Indian divisions at Imphal.

[18] After some vicious fighting, the British captured Meiktila on 3 March and swept down the road to Mandalay, which was defended by 400-year-old Fort Dufferin complete with high thick walls and a wide moat.

[citation needed] The last major mission of the 12th was an overnight where the crews spent the night under the wings of their B-25s at Rameree, near Rangoon, and took off the next morning to bomb Ban-Takli airfield north of Bangkok, Thailand.

[19] Although nominally stationed at Langley Air Force Base, Virginia, the unit was neither manned or equipped and only existed on paper.

President Truman's reduced 1949 defense budget required reductions in the number of Air Force groups to 48,[20] and the 12th was inactivated on 10 September 1948.

These aircraft, however, were rejected as Republic Aviation had equipped them with an engine that was incapable of supporting the extended bomber escort missions projected by SAC.