Question: How did many multiracial individuals, of the nation that started making an unlicensed version of the 40mm at the beginning of WWII, attain social and economic advantages?

full_context: Document 1: Race (human categorization): Since the early history of the United States, Amerindians, African–Americans, and European Americans have been classified as belonging to different races. Efforts to track mixing between groups led to a proliferation of categories, such as mulatto and octoroon. The criteria for membership in these races diverged in the late 19th century. During Reconstruction, increasing numbers of Americans began to consider anyone with "one drop" of known "Black blood" to be Black, regardless of appearance.3 By the early 20th century, this notion was made statutory in many states.4 Amerindians continue to be defined by a certain percentage of "Indian blood" (called blood quantum). To be White one had to have perceived "pure" White ancestry. The one-drop rule or hypodescent rule refers to the convention of defining a person as racially black if he or she has any known African ancestry. This rule meant that those that were mixed race but with some discernible African ancestry were defined as black. The one-drop rule is specific to not only those with African ancestry but to the United States, making it a particularly African-American experience.
Document 2: Anti-aircraft warfare: Britain had successful tested a new HAA gun, 3.6-inch, in 1918. In 1928 3.7-inch became the preferred solution, but it took 6 years to gain funding. Production of the QF 3.7-inch (94 mm) began in 1937; this gun was used both on mobile carriages with the field army and transportable guns on fixed mountings for static positions. At the same time the Royal Navy adopted a new 4.5-inch (114 mm) gun in a twin turret, which the army adopted in simplified single-gun mountings for static positions, mostly around ports where naval ammunition was available. However, the performance of both 3.7 and 4.5-in guns was limited by their standard fuse No 199, with a 30-second running time, although a new mechanical time fuse giving 43 seconds was nearing readiness. In 1939 a Machine Fuse Setter was introduced to eliminate manual fuse setting.
Document 3: Multiracial Americans: For African Americans, the one-drop rule was a significant factor in ethnic solidarity. African Americans generally shared a common cause in society regardless of their multiracial admixture, or social/economic stratification. Additionally, African Americans found it, near, impossible to learn about their Indigenous American heritage as many family elders withheld pertinent genealogical information. Tracing the genealogy of African Americans can be a very difficult process, especially for descendants of Indigenous Americans, because African Americans who were slaves were forbidden to learn to read and write, and a majority of Indigenous Americans neither spoke English, nor read or wrote it.
Document 4: Multiracial Americans: In the colonial years, while conditions were more fluid, white women, indentured servant or free, and African men, servant, slave or free, made unions. Because the women were free, their mixed-race children were born free; they and their descendants formed most of the families of free people of color during the colonial period in Virginia. The scholar Paul Heinegg found that eighty percent of the free people of color in North Carolina in censuses from 1790–1810 could be traced to families free in Virginia in colonial years.
Document 5: Anti-aircraft warfare: German air attacks on the British Isles increased in 1915 and the AA efforts were deemed somewhat ineffective, so a Royal Navy gunnery expert, Admiral Sir Percy Scott, was appointed to make improvements, particularly an integrated AA defence for London. The air defences were expanded with more RNVR AA guns, 75 mm and 3-inch, the pom-poms being ineffective. The naval 3-inch was also adopted by the army, the QF 3 inch 20 cwt (76 mm), a new field mounting was introduced in 1916. Since most attacks were at night, searchlights were soon used, and acoustic methods of detection and locating were developed. By December 1916 there were 183 AA Sections defending Britain (most with the 3-inch), 74 with the BEF in France and 10 in the Middle East.
Document 6: Multiracial Americans: Americans with Sub-Saharan African ancestry for historical reasons: slavery, partus sequitur ventrem, one-eighth law, the one-drop rule of 20th-century legislation, have frequently been classified as black (historically) or African American, even if they have significant European American or Native American ancestry. As slavery became a racial caste, those who were enslaved and others of any African ancestry were classified by what is termed "hypodescent" according to the lower status ethnic group. Many of majority European ancestry and appearance "married white" and assimilated into white society for its social and economic advantages, such as generations of families identified as Melungeons, now generally classified as white but demonstrated genetically to be of European and sub-Saharan African ancestry.
Document 7: Multiracial Americans: Laws dating from 17th-century colonial America defined children of African slave mothers as taking the status of their mothers, and born into slavery regardless of the race or status of the father, under partus sequitur ventrem. The association of slavery with a "race" led to slavery as a racial caste. But, most families of free people of color formed in Virginia before the American Revolution were the descendants of unions between white women and African men, who frequently worked and lived together in the looser conditions of the early colonial period. While interracial marriage was later prohibited, white men frequently took sexual advantage of slave women, and numerous generations of multiracial children were born. By the late 1800s it had become common among African Americans to use passing to gain educational opportunities as did the first African-American graduate of Vassar College Anita Florence Hemmings. Some 19th-century categorization schemes defined people by proportion of African ancestry: a person whose parents were black and white was classified as mulatto, with one black grandparent and three white as quadroon, and with one black great-grandparent and the remainder white as octoroon. The latter categories remained within an overall black or colored category, but before the Civil War, in Virginia and some other states, a person of one-eighth or less black ancestry was legally white. Some members of these categories passed temporarily or permanently as white.
Document 8: .55 Boys: The .55 Boys was adopted and manufactured alongside the Boys Anti-Tank Rifle in 1937 throughout the Commonwealth of Nations by firms such as Kynoch. However, when the United Kingdom entered World War II, the .55 Boys round was soon found to be insufficient against even early war Axis tanks in late 1939 and 1940. However, the United Kingdom had to rely on the .55 Boys round for several years because no better infantry anti-tank weapons were available. When the PIAT anti-tank weapon was introduced in 1943, the shaped charges it fired proved to be far more effective against enemy armor than the .55 Boys round had The Boys rifle was phased out of service as the PIAT became the British military's primary handheld anti-tank weapon. Despite its lack of effectiveness as an anti-tank weapon, the .55 Boys was used throughout World War II in both the Pacific and Atlantic theaters and also saw use during the Winter War and Continuation War by Finland. By the conclusion of World War II, the .55 Boys was no longer used in any major capacity.
Document 9: Anti-aircraft warfare: The British had already arranged licence building of the Bofors 40 mm, and introduced these into service. These had the power to knock down aircraft of any size, yet were light enough to be mobile and easily swung. The gun became so important to the British war effort that they even produced a movie, The Gun, that encouraged workers on the assembly line to work harder. The Imperial measurement production drawings the British had developed were supplied to the Americans who produced their own (unlicensed) copy of the 40 mm at the start of the war, moving to licensed production in mid-1941.
Document 10: Multiracial Americans: Multiracial Americans are Americans who have mixed ancestry of "two or more races". The term may also include Americans of mixed-race ancestry who self-identify with just one group culturally and socially (cf. the one-drop rule). In the 2010 US census, approximately 9 million individuals, or 2.9% of the population, self-identified as multiracial. There is evidence that an accounting by genetic ancestry would produce a higher number, but people live according to social and cultural identities, not DNA. Historical reasons, including slavery creating a racial caste and the European-American suppression of Native Americans, often led people to identify or be classified by only one ethnicity, generally that of the culture in which they were raised. Prior to the mid-20th century, many people hid their multiracial heritage because of racial discrimination against minorities. While many Americans may be biologically multiracial, they often do not know it or do not identify so culturally, any more than they maintain all the differing traditions of a variety of national ancestries.
Document 11: Anti-aircraft warfare: As aircraft started to be used against ground targets on the battlefield, the AA guns could not be traversed quickly enough at close targets and, being relatively few, were not always in the right place (and were often unpopular with other troops), so changed positions frequently. Soon the forces were adding various machine-gun based weapons mounted on poles. These short-range weapons proved more deadly, and the "Red Baron" is believed to have been shot down by an anti-aircraft Vickers machine gun. When the war ended, it was clear that the increasing capabilities of aircraft would require better means of acquiring targets and aiming at them. Nevertheless, a pattern had been set: anti-aircraft weapons would be based around heavy weapons attacking high-altitude targets and lighter weapons for use when they came to lower altitudes.
Document 12: Anti-aircraft warfare: Some nations started rocket research before World War II, including for anti-aircraft use. Further research started during the war. The first step was unguided missile systems like the British 2-inch RP and 3-inch, which was fired in large numbers from Z batteries, and were also fitted to warships. The firing of one of these devices during an air raid is suspected to have caused the Bethnal Green disaster in 1943. Facing the threat of Japanese Kamikaze attacks the British and US developed surface-to-air rockets like British Stooge or the American Lark as counter measures, but none of them were ready at the end of the war. The Germans missile research was the most advanced of the war as the Germans put considerable effort in the research and development of rocket systems for all purposes. Among them were several guided and unguided systems. Unguided systems involved the Fliegerfaust (literally "aircraft fist") as the first MANPADS. Guided systems were several sophisticated radio, wire, or radar guided missiles like the Wasserfall ("waterfall") rocket. Due to the severe war situation for Germany all of those systems were only produced in small numbers and most of them were only used by training or trial units.
Document 13: Anti-aircraft warfare: After World War I the US Army started developing a dual-role (AA/ground) automatic 37 mm cannon, designed by John M. Browning. It was standardised in 1927 as the T9 AA cannon, but trials quickly revealed that it was worthless in the ground role. However, while the shell was a bit light (well under 2 lbs) it had a good effective ceiling and fired 125 rounds per minute; an AA carriage was developed and it entered service in 1939. The Browning 37mm proved prone to jamming, and was eventually replaced in AA units by the Bofors 40 mm. The Bofors had attracted attention from the US Navy, but none were acquired before 1939. Also, in 1931 the US Army worked on a mobile anti-aircraft machine mount on the back of a heavy truck having four .30 caliber water-cooled machine guns and an optical director. It proved unsuccessful and was abandoned.
Document 14: Anti-aircraft warfare: Poland's AA defences were no match for the German attack and the situation was similar in other European countries. Significant AA warfare started with the Battle of Britain in the summer of 1940. 3.7-inch HAA were to provide the backbone of the groundbased AA defences, although initially significant numbers of 3-inch 20-cwt were also used. The Army's Anti-aircraft command, which was under command of the Air Defence UK organisation, grew to 12 AA divisions in 3 AA corps. 40-mm Bofors entered service in increasing numbers. In addition the RAF regiment was formed in 1941 with responsibility for airfield air defence, eventually with Bofors 40mm as their main armament. Fixed AA defences, using HAA and LAA, were established by the Army in key overseas places, notably Malta, Suez Canal and Singapore.
Document 15: Black people: From the late 19th century, the South used a colloquial term, the one-drop rule, to classify as black a person of any known African ancestry. This practice of hypodescent was not put into law until the early 20th century. Legally the definition varied from state to state. Racial definition was more flexible in the 18th and 19th centuries before the American Civil War. For instance, President Thomas Jefferson held persons who were legally white (less than 25% black) according to Virginia law at the time, but, because they were born to slave mothers, they were born into slavery, according to the principle of partus sequitur ventrem, which Virginia adopted into law in 1662.
ground_truth: Many of majority European ancestry and appearance "married white" and assimilated into white society
sub_queries: Who started making an unlicensed version of the 40mm at the beginning of the war? Answer: Americans
How did many multiracial Americans attain social and economic advantages? Answer: Many of majority European ancestry and appearance "married white" and assimilated into white society