The Sierra Bombardment Group was a provisional

United States Army Air Corps The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical ri ...

organization. It was established on 8 December 1941 at

Minter Field Minter may refer to: Places in the United States *Minter, Alabama, an unincorporated community *Minter Village, California, an unincorporated community *Minter City, Mississippi * Minter, Washington State, Hendersen Bay's northwest shore, Carr Inle ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

. It consisted of air crews and ten

B-17E Flying Fortress The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Relatively fast and high-flying for a bomber of its era, the B-17 was used primarily in the European Theate ...

es formerly assigned to the 7th Bombardment Group

32d Bombardment Squadron The ROMP is a reduced instruction set computer (RISC) microprocessor designed by IBM in the late 1970s. It is also known as the Research OPD Miniprocessor (after the two IBM divisions that collaborated on its inception, IBM Research and the Off ...

and

427th Bombardment Squadron 4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. In mathematics Four is the smallest c ...

. In addition, thirty five

B-25 Mitchell The North American B-25 Mitchell is an American medium bomber that was introduced in 1941 and named in honor of Major General William "Billy" Mitchell, a pioneer of U.S. military aviation. Used by many Allied air forces, the B-25 served in ...

medium bombers of the

17th Bombardment Group The 17th Bombardment Group is an inactive United States Air Force unit. The group was last stationed at Hurlburt Field, Florida. The Group is a direct successor to the 17th Pursuit Group, one of the 15 original combat air groups formed by the ...

Second Air Force The Second Air Force (2 AF; ''2d Air Force'' in 1942) is a USAF numbered air force responsible for conducting basic military and technical training for Air Force enlisted members and non-flying officers. In World War II the CONUS unit defended ...

, Pendleton Army Airfield,

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idah ...

, were also assigned. The squadrons were located in the Western United States and were awaiting transfer to the Philippines in early December 1941. After the

Pearl Harbor Attack The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, ...

, the provisional unit was formed. It performed coastal patrols for a short time stationed at

Muroc Army Airfield Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is ...

, but as the conditions in the Philippines worsened, the B-17s departed via

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only ...

on 17 December. However upon arrival at

Hickam Field Hickam may refer to: ;Surname * Homer Hickam (born 1943), American author, Vietnam veteran, and a former NASA engineer ** October Sky: The Homer Hickam Story, 1999 American biographical film * Horace Meek Hickam (1885–1934), pioneer airpower advo ...

, the aircraft were pressed into service for defensive reconnaissance patrols. Three B-17s were released and were allowed to depart for

Mindanao Mindanao ( ) ( Jawi: مينداناو) is the second-largest island in the Philippines, after Luzon, and seventh-most populous island in the world. Located in the southern region of the archipelago, the island is part of an island group of t ...

, but were diverted to

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...

Netherlands East Indies The Dutch East Indies, also known as the Netherlands East Indies ( nl, Nederlands(ch)-Indië; ), was a Dutch colony consisting of what is now Indonesia. It was formed from the nationalised trading posts of the Dutch East India Company, whi ...

, where they were assigned to evacuated 19th BG components that were operating from

Singosari Airfield Juanda International Airport (JIA) ( id, Bandar Udara Internasional Juanda) , is an international airport located in Sedati, Sidoarjo. It is now the third busiest airport in Indonesia (after Soekarno-Hatta and Ngurah Rai airport). This ai ...

. The remainder stayed at Hickam until 10 January when they flew to Australia via Christmas Island; Kanton Island and Fiji where the aircraft were held for almost a week while Vichy French guerrilla activity was put down. Upon arrival at Townville,

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

, unit was assigned to the

19th Bombardment Group 19 (nineteen) is the natural number following 18 and preceding 20. It is a prime number. Mathematics 19 is the eighth prime number, and forms a sexy prime with 13, a twin prime with 17, and a cousin prime with 23. It is the third full ...

as replacements. The B-25 Mitchells remained in Oregon and continued to provide coastal antisubmarine patrols along the Northwest Pacific Coast. However, the available aircraft were not equipped with radar or other devices, and detection of enemy submarines depended solely on eyesight. The antisubmarine aircrews occasionally mistook whales and floating logs for Japanese submarines, They frequently reported and attacked enemy submarines, but rarely confirmed results. A B-25 crew claimed they bombed a submarine near the mouth of the Columbia River on 24 December 1941. They claimed it sank, but in fact no Japanese submarine was sunk off the West Coast during World War II. The unit was discontinued in early February 1942

References

* Maurer, Maurer (1983). Air Force Combat Units Of World War II. Maxwell AFB, Alabama: Office of Air Force History. .
Battle against the U-Boat in the American Theater
{dead link, date=May 2018 , bot=InternetArchiveBot , fix-attempted=yes Military units and formations of the United States Army Air Corps Ad hoc units and formations of the United States Military units and formations established in 1941